Sosoida Koi ga Michitara Ai

Hibiki Kitami, a university student who works part-time at "Café Futaba", works diligently every day with the goal of taking over the coffee shop run by his grandparents in the future. One day, a junior from the same university, Ryousuke Fujinami, arrives at "Futaba" as a new part-time worker. Fujinami, quickly fits in with his innate cheerfulness, but Kitami, who is too serious, remains out of place no matter how much time passes. However, Fujinami becomes unusually attached to Kitami as well.

(Source: Ichijinsha, translated)