Pretty good as far as RPGM games go, even if not for gameplay reasons so much. But I attribute that to the limitations of the format rather than the game itself.
Art is good, despite the comments on the thread about AI CGs, which I can't confirm or deny because I'm no expert on discerning signs of AI art unless there's a sixth finger or other body parts merging with clothing, which I didn't see. What I will say is that the art fits the game. I liked the style.
As for plot, if you've ever played the PS2 game Fatal Frame II: Crimson Butterfly, this game's plot is around 70-75% that. Or at the very least, it's clear where Bonds of Yachiyo gets inspiration from. It's a story of two best friends who must come to terms with having to part one day, no matter how close they may be. I will say that I didn't expect to get any feels from this - I was just looking for a quick fap to be honest - but I stuck with the story and got a semi-good or decent one. It's not the best narrative I've seen in my life, but I will give it praise for eliciting emotions other than horniness out of me.
Oh, and make no mistake: it's got horror, more so than most games in the format, so if you scare easily, I must caution you that about 80-85% of the way through the game the game dials up that horror to 11. It's probably the most horror I've seen in a RPGM, or even any h-game. During the aforementioned 80-85% part of the story, I felt slightly unnerved, and the visual and audio design are pretty good for a RPGM, I must say. Good in the sense that both help support the horror atmosphere.
Gameplay-wise, it's got its... uniqueness, thanks to its insistence on leaning on horror. There are no standard RPGM fare fights where you go through menus to hit Attack or Skill or Defend. The parts where you can fight enemies, you just walk up to their sides or back and cut them down that way. Other times, you're just sneaking and staying out of enemies' lines of sight while you look for key items in order to progress through the story. It's nothing revolutionary, and to some that might be boring even for a RPGM, but I personally didn't mind. The gameplay at least fits the tone the game is trying to showcase. This game would be even better if it was in Unity or Unreal Engine, those would definitely scare my soul from my body. If it was in those formats, coupled with the incorporation of some rudimentary but sufficient combat and stealth mechanics, I would have awarded this game five stars.
I'd rate it 4.5. The .5 of that rating is carried by the game having references to Fatal Frame II which is my gold standard for survival horror games.
Not a bad game. It doesn't feel like a RPGM that someone just cranked out for a quick buck - the plot at the very least required more brainpower to utilize, more than what a desperate developer would typically use. If you have two or three hours to kill, I would recommend a pure playthrough to get the best ending, then if you want what you initially came for, just go to the gallery in the title menu and just approach the stars in the gallery, where you can unlock h-scenes that do not have major spoilers, or all at once.