TL;DR - is it worth your time?
At first I thought this was just a game with wasted potential but the more routes I played, the more I came to realize what this game really is: lazy. If you enjoy NTR, and have literally nothing else to play, then you might as well try it, but you will be disappointed.
STORY
You play as Bell, a young man in some bumfuck village who is in love with his childhood friend Lumia. Lumia is off in some far away town pursuing her dream of becoming a singer in order to bring joy to the lives of the masses. One day your mom gets a letter from Lumia saying she's become the lead singer of a band and wants you to come see her perform. You mom also informs you that she's gonna bankroll this little trip of yours and encourages you to go confess your feelings. Based as hell mom.
You hop on a boat, sail to the town Lumia's in and are given 5 days before your return ship leaves in order to confess your love for her. The final bit of this prologue that also pseudo tutorializes the game is you and Lumia spend the first day of your trip going out on a date to explore the city. During this date, the two of you are introduced to all the potential villains of the game as you traverse the city before finally ending the first day and beginning the game in earnest.
Gameplay
The core gameplay boils down to how you spend your days and the system is simple and straightforward: going on dates with Lumia whenever possible will build affection for you and lead to a "victory" state (Happy end), and viewing erotic scenes with her and other people will build her affection for them and lead to a "failure" state (various NTR ends). If you click on the heart events, bad stuff happens, if you go on dates, good stuff happens. Already this system introduces a series of problems which I'll get into shortly. Lastly, each day is split into a morning, evening and night phase. Each phase of the day can loosely be grouped as such: Mornings are for going on dates with Lumia, evenings are for watching her concerts, and nights are for watching her get fucked (playing in the best interest of the MC will result in you never seeing a night phase).
When it comes to the NTR, the game plays out like this: when given the option to see an erotic scene, you will essentially be peeping on Lumia, your vision of what's actually happening being obscured enough that you never really know it's her. You're shown a darkened or blocked CG before your character gets nervous about watching and leaves. In order to see what's ACTUALLY going on, you have to then go to the magical circle at the edge of town that the character uses to see Lumia's true feelings, that also acts as a recollection room. Once going through that loading screen, you are able to talk to this avatar of Lumia to see what her heart desires (what route she's on) while also being able to check on specifically how she got fucked, and the accompanying plot that is meant to explain the encounter.
Review
I have a lot to complain about when it comes to this game, but since we were just talking about the recollection room, why not start there. Right off the bat and this is gonna seem like a petty annoyance but it really got me - when entering the recollection room you are prompted with a tutorial of what it is, that consists of two pages of text followed by a confirmation YES/NO menu. The problem is that the default answer is "no" so when players who want to enter this fucking room for the 20th time and are just mashing buttons to get through the text, you can pretty easily hit "no" without intending to. Keep in mind, you MUST ENTER this room many times per route in order to understand the plot of the game, it is required. Also there's no reason for it to default to "no" since the room is off to the side, out of the players way and out of the way of any paths you would be taking - it's not possible to accidentally hit the recollection room. I know that seems silly, but fuck, it really bothered me. Next up, for whatever reason, they made the recollection room the one place that you use in order to check on Lumia's feelings. In literally every single other game like this I've played, that's always just some shit they put in the pause menu. Why in the world would they put what should be a menu feature behind a loading screen in the recollection room? It makes no god damn sense! Or that's what I would say if this "feelings meter" was fleshed out at all. 95% of the game will consist of Lumia's feelings saying "none", with it only changing once she gets locked into a route. But she only gets locked into a route once you finish like ALL the erotic scenes for any particular villain, so what the fuck is the point? There's no subtle gradation of her changing mood as she grows more attached to the antagonists its just a binary flip, which actually pretty neatly tracks with how she behaves in the narrative too.
With that out of the way, lets talk about what really breaks the game in my view. There is a ludonarrative conflict that arises as a result of the way this game's core gameplay loop has been implemented, and when coupled with some extremely lazy writing that manages to break even my suspension of disbelief (I'm a hardcore NTR enjoyer so, you know I'm willing to look past a lot of insane plot contrivances) then what you're left with is a dull, vapid, and ultimately soulless game that manages to completely divorce the desired outcome of the game from that of how the player must interact with it.
In NTR games there's inherently a disconnect between what the player wants and what the main character wants - we want to see the girl get stolen, and the MC doesn't. However we're playing the game, so naturally we self-insert, meaning that in games like these that aren't telling a linear story, one of two things has to be true in order for the game to be satisfying to the target demo. Either the gameplay or events have to be tuned in such a way that it is difficult to avoid the girl being stolen (at least on the first playthrough), OR the players have to be given room to intentionally sandbag which leads to a "failure" state. This game does neither of those things. Every outcome is a binary check that YOU click on. This leads to the problem where if you wanna play with any sense of believability, in which your girl gets stolen, then the route is way too simple - just don't click on the hearts, and don't turn down dates with Lumia. We as the player have to essentially hit a button that says "yes fuck my girlfriend please". Paradoxically in the game about Netorare, we as the player have to engage in Netorase which feels really fuckin weird. The girl being stolen needs to happen in spite of my efforts for an NTR game to mean anything. Now that doesn't mean in spite of my BEST efforts, surely not, in games like these if you're playing well, then a happy end ought to exist, but there needs to be elements that allow these "bad" outcomes to happen. Take Scars of Summer for example, that game is structurally similar to this one, though WAY more fleshed out. You play as a guy trying to confess to a girl who loves you, all while antagonists are trying to steal her from you. However in that game, you're given other shit to do that allow the NTR to happen in spite of you trying. Time moves on its own in that game, so while you're off trying to collect memories in some cave to get the good ending, or working your job to get enough money to buy the stuff you need, there's a chance another guy is fucking your girl and taking your place in her heart. The events don't require you to click on them to happen, they happen whether you want them to or not. You as the PLAYER get the girl stolen from you, you don't just literally give her away.
Another problem with how the erotic scenes are implemented is that only scenes that initiate during your dates are exclusive to other scenes, meaning you can trigger several different routes worth of scenes back to back to back. If you care about the believability of the world, then this means that the game actively punishes you for exploration. I'll give you an example of my first playthrough and how it kinda made me roll me eyes at the end of just the first day. Before I go into it, it's important to keep in mind that Bell and Lumia are two childhood friends who are in love with each other, are going on regular dates, and most importantly, are virgins.
So my first real day of gameplay starts (day 2) and I decide to wander around the city a bit before my date with Lumia, so I head to the slums since it's right next to my house and wouldn't you know it, Lumia is in a tent giving a handjob to a hobo. I proceed from there to the beach to meet with her for our date. During the date I head straight north off the beach and the first building I encounter has another heart icon, so I click it, and Lumia goes off with some lady for a massage that I would later find out was just that lady rubbing Lumia's tits so good that she came multiple times. With my prospective girlfriend off cumming her brains out in a massage parlor, that left me with nothing else to do in the town so I proceeded to the evening phase. Went to Lumia's concert, but declined the date at the end because I was worried about my "affection" with her climbing too fast. Exiting the concert moved me into the "night phase", so I went exploring some more. I headed upstairs in the venue only to find Lumia sucking off one of her bandmates. When I left and explored the docks I found Lumia being blackmailed by a fan into letting him thigh-fuck her while playing with her tits, and my night finally culminating with walking into a building to find Lumia titty fucking some rich dude. On my FIRST DAY THERE, my virgin girlfriend, who sent me a romantic letter to sail across the sea to come be with her, makes 4 different men cum in various ways and let some chick bring her to multiple orgasms via aggressive nipple play. I'm sorry but that's just a stupid amount of shit to happen in one evening, there needed to be limits on what she can be doing. She's fuckin sprinting from one cock to the next in order to get there in time for me to stumble across it, it's just silly.
This game's writing also falls into a common trap of lazy NTR writing and that's that there just isn't enough character development to justify how any ending (besides the happy end) happens. Essentially every route involves Lumia being either blackmailed or coerced into sex, except the hobo route weirdly enough. Now during the first 3 scenes in each route, Lumia is staunchly against the sexual acts that are being done to her but then scene 4 rolls around and with no dialogue or exposition, her mood is swapped on a dime. For her bandmates, she decided that being a meat toilet for them is actually the best form of bonding she can do to achieve the greatest harmony with them; for the rich prick she gets mind broken into being a sex slave randomly; for the fan who was *raping her* she has like 1 line of dialogue where she says like "oh he's actually a good guy by the way" and then proceeded to do a private pole dance show for him and his friends in which she sucks his cock on stage in front of everyone (what???). It's all bonkers. Like, fuck me, for the blackmailing Kid route, the writer was truly taking the piss, in that he had her literally become a cock obsessed cum slave due to a MAGIC SPELL the kid casts. It's not even foreshadowed or brought up at all, they unironically in 2 throwaway lines go basically "Wow I didn't know such magic existed" and then call it "Magic That Makes You Like Sex", then proceed with a scene in which Lumia is gleefully getting gangbanged.
Lastly, and while I'm on the topic of routes, all the art is reused. Not a single route has unique art, it's all shared with at least one other route. It ruined the replayability of the game for me because at a certain point I wasn't even getting rewarded with new art. And I sure as hell wasn't getting rewarded with plot.
Conclusion
If I'm being honest, I had no intention of doing more than one route in this game. After I got the first ending, I had no drive to open it back up and go for another playthrough. On that first go, I figured "Well, it wasn't great, but there's something here, they just didn't explore it to the full potential". I wanted to give a rating just so I could talk about some of the missteps and where I thought the game could have gone to really flesh it out and hone what was there. But I figured before I do that, I probably owe it to the people reading that I 100% the game, so I'm not missing anything with the review. And as I played, the more and more annoyed and angry with it I got. It became clear that this game's quality wasn't just a product of "missed potential", but rather willful laziness and poor design. Like the TL;DR says at the top, if you've got nothing to play, fuck it, try this, but until then, go play the back catalogue of actually good games on this site.