When in doubt, it is always good to resort to obejctionism. So lets use this lense to view this game through.
But first, a spoilerless TL;DR:
This game has no tension storywise. The main characters's two best friends get mindcontrolled at the start of the game, then tortured and raped. In all the hentai scenes, the girls in it gets tortured and raped in EXTREMELY graphic manners (I am talking about blood), and the kink of the game's author, seems to be the extreme graphic torture of said women in this game.
Is it NTR? - One of the Toybox Killer's victims was married. If I told a story about this woman's run in with said killer, would it be NTR?
Is it then Hentai/Porn? - This game uses whatever logic it wants all over the place. At one hand it uses hentai logic (Oh no! My tits are literally getting ripped off! But I won't scream, but talk in an otherwise standard conversational tone). In another it uses real life logic (I have PTSD, so I am going to stab the guy who saved me and the hero of this story to death).
(I am not hyperbolic in these examples btw. Both these things happen in the game)
Should you play it? - If you are into female genital mutiliation (Again, not being hyperbolic) then sure, go ahead. If you like no tension in the story, which is the case as the second the bad guy in the game uses his magic control spell (Which happens like at the very start of the game), as the story is concerned, the Hero's friends are gone and lost forever. Even if you kill the bad guy, his childhood friends are still mind controlled (By him??? Somehow???), and want to kill the hero (That is still weakened from the bad guy. Because again, this game uses whatever logic it wants just to have an excuse to torture the women more in this game)
So you tell me. Does a game where you have allready lost at the start of the game (Because either the MC dies, or he gets killed in his sleep. Thats it. Thats the only two endings) sound interesting? Where the "hentai" is literally just torture and rape, with no way of saving the subjects of this torture and rape sound fun?
Further more, its a LOOOOOONG game with drawn out fight sequences. Does this grind seem fun?
If this sounds fun and sexy to you,t hen knock yourself out. To go back to the Toybox killer, he died of a stroke in a jailcell before his sentence truelly started. I am convinced he was handed a copy of this game, and this is what made him get a stroke. Because even to him, he would go "wtf bro this is too far"
On a final note, look, I get it. Ugly bastard NTR is hard to come by. This game is not just it. Starworks have good ones. So does Kagura games.
Go play those ones instead.