Kisaragi no Hougyoku

2016/Infinitemangastudios, Waiting for you guys

Fujiwara Toru is a transfer student. At first glance he seems to be a generic, awkward teenager, but there is more to him than meets the eye. Sangu academy has a tradition called Ren. each year student choose a different grade partner, and all non partnered people are alone.

Steam store (publisher's text)