Gamerip game "Cross Days" from the Studio 0verflow, which is part of the series School days...

Yuki-kun met Kotonoha in the beginning of the second semester in the student library. They had no special relationship - only met and chatted in the library. On the horizon there is a new character the friend of his younger sister Pei - a girl named Rock. At first sight they liked each other, but Yuki heard rumors that the Rock's in love with his best friend Makoto, who in turn is Dating a girl named Kotonoha. Of course, our hero did not dare to ask directly about it, and asked (for some reason) to Kotonoha for help. Actually and this begins a complicated romance with many different arcs and endings...