Responses
In Japan (and other countries), if you're older than 25/30 you're not considered young anymore but an adult (and by consequence an uncle... In this case mc is calling himself uncle bc the other is a high school student, if he were older probably the uncle-joke wouldn't be there). It's a bit sad, but I guess it's due to the great importance given to age, just being one year older than someone makes a dramatic difference. But that's culture ╮( ̄▽ ̄)╭
Thanks translator, good job on a cute manga. My only issue is actually a cultural thing. Explain how someone in their twenties honestly considers themselves an uncle!? You’ve got to hit your forties to be considered middle aged.