If you want to write a fanfic about Tezuka Kunimitsu, you should write about his moon-like tenderness, his possessiveness hidden deep in his bones, and his visible charm.
The story begins with the stunning first encounter between Natsakura Kimiya and Kunimitsu Tezuka, and continues with him asking: "Can our cooperation period be extended to a lifetime?" The story never ends.
I'm not accommodating you, because I like you so I like everything about you.
It wouldn't work if it weren't for you. All my feelings and words are due to you. It can only be you.
(The timeline is not completely consistent with the anime, but the general trend is similar)
Purpose: Tezuka Kunimitsu's birthday celebration in 2023