Hito wa Naze Hataraka Nakerebanaranai no ka

For ten years Kousuke has followed Tomonari-senpai, from high school to college and now the company at which they both work, all the while telling himself that their friendship is enough for him. Kousuke's world tips upside down when he finds out two shocking facts in one evening that change his perspective on Tomonari drastically.