Kataude no Zarigani - one-armed crayfish

"Going against the grain? That's just a kind of rebellious phase." That's what high school student Nozaki Yuuta believed, making it his principle to live by going with the flow. And because of that, he spent every day in peace. However, through his classmate Miyoshi Misaki, who went against the grain on absolutely everything, he starts to confront his own true feelings.

[From Steam]