I like that the backstory is not the standard "my parents beat me"/"my parents left me" but something that served in a way that will compliment the "opening the door" oddity.
"Tomoko opened the door for me when no one else would, now I would open the door for her when no one else would"
@StaticTransit i kinda disagree.
I already don't really care about her to begin with
most of the readers as well, thats why this chapter is introduced: so we care about her and understand why does she willing to go such length to meet tomoko.
cramming all that into not even an entire chapter also diminishes the impact for me
tbh i think 1 chapter backstory is the best course of action here, because the character was just introduced in this arc. Adding another chapter will just diminish people's hype since this is just right before the climax. Although a deeper exposition would be nice: why is she considered brazen as a kid, why is a shy and timid kid considered as a troublemaker, etc