Yuuzutsu wa Ai ni Tokeru

Shintaro Kuze, a fledgling writer, ends up staying at his former teacher's house. There, he is also taken care of by a calligrapher named Shogo Kuzuki, who the shy Kuse finds quite uncomfortable. One day, Shintaro is asked to teach Kuzuki, who has written a study piece. At first, he is reluctant to help him, but gradually he is overwhelmed by Kuzuki's work, which he can't imagine from his usual vivacious personality...

(Source: Pixiv, translated)