"DEGENERATION" is the name of a training simulation game (SLG), revived to tell the story of Aoi, who by some chance becomes your pet, and spends 45 days with you.
This game is an interactive sex simulation game, where the commands you choose influences the attitudes of those you meet and causes different situations to occur.
There is a normal mode and a hard mode; the former being easy to undress & enjoy fucking her. In the latter, the girl resists and this mode has a high degree of difficulty. While she is in a relaxed mood you can undress her.
Despite becoming the first volunteer soldier ever, our protagonist who has never held a proper job in his life starts off by protecting the secret of the one and only pilot who can protect the battleship.