Hibari ga Naitara Tsukamaete

Enomoto, currently a college student, often finds himself reminiscing the days spent with his childhood friend Shimura, who had always been beside him up until six years ago. Due to a sudden transfer, Enomoto didn't get to ask Shimura where he was moving and he hadn't heard anything from him since. Until one day, he suddenly reunites with Shimura in his Philosophy class in college. Enomoto is over the moon, but Shimura seems to feel differently...

(Source: Kadokawa, translated)