#particularly the surname thing is something you generally try to avoid in fiction but idk maybe it was an oversight by the writers

[project-sekai-facts]

hello!!! i was wondering, outside of the "playable" siblings, which characters have siblings that they've talked about/we've seen before?

Honami has a younger brother (age unknown). He is not named and rarely mentioned, and as far as i remember he has never appeared in any stories (unvoiced/no L2D obviously)

Minori has a younger brother in elementary school (6-12 years old). He is unnamed and doesn't have a L2D model, but has some unvoiced dialogue

Airi has a younger sister and an older sister. The younger sister is probably quite close in age to her given her interactions with a 7-ish year old Airi. I don't recall the older one ever appearing. Neither is named but the younger sister has unvoiced dialogue.

Toya has two older brothers. One is a professional musician (age unknown) and one is studying music at a conservatoire in New York (~19-early 20s). They are not named and have not appeared in the story.

Emu has two brothers who are significantly older than her and work managing PXL (Keisuke, ~31 & Shousuke, ~28), and an older sister (Hinata, ~21) who is in college

Mizuki has an older sister called Yuuki (22) who is studying at university in France

Every other MC is an only child or their sibling is another MC. NPC-wise, there's the Kotakis and the Yoshizakis. Kotaro has a much younger brother who is still a toddler. Sakurako is confirmed to be an only child, but other than that there's no confirmation for anyone (a lot of them are probably only children though). As far as I remember, no one is stated to have an aunt or uncle either.