It's just the onsen route. I don't buy his reason that it's because their journey with Yuma has ended, hence the separation of this route from the main game. I suspect the real reason is, as you can see in the title, Hana's revenge at Tatsuki. I smell real NTR coming. It's a move from his part to be able to mix in some real NTR by separating this in defense from his nts supporters because he can just say it's a different game from the wholesome NTS main game. Although I really can't tell if it's NTR when Tats is basically asking for it because in the recent update,