Aiteru Door Kara Shitsurei Shimasu yo

Honda's life is anything but exciting; he works as a public tax accountant for the city. Honda and Shunji are cousins, but when Shunji's parents passed away, he was adopted into Honda's family. Yet, Shunji went missing for 10 years. Now, when Honda is reunited with his younger brother, his life is flipped up-side-down! What do they have to say to each other after all these years?

(Source: Juné Manga)

Included is an extra chapter with the three Honda's brother and a side story, Diary of an Errand.