Sweet Pool (スウィート プール) is a boys's love game by Nitro+chiral. It was released 19.12.08 and is a PC game (there is an unofficial chinese port by otomedream). It was illustrated by Kurumazaki Mayuki.
Youji is a little bit nervous because he goes to school for the first time in several months. From that day, his surroundings gradually change.... Tetsuo unexpectedly approaches Youji. Youji asks Tetsuo why, but he never answers.... Youji gets scared of Tetsuo. Zenya also approaches Youji at the same time. One day, Zenya suddenly whispers Youji, "It's all your fault...." Strange pain.... Vivid nightmare.... Are they just illusions? What are Tetsuo and Zenya's purpose?
Disclaimer* Quote taken from The Visual Novel Database
: Youji basically starts expelling meat monsters from his behind. Having had weak health all his life and only just getting back into school, he finds it hard to fit in. Shironuma Tetsuo is intitally cold, but slowly begins to warm up to Youji after finding out his secret.