Responses
That and the sister looks nothing like the gremlin she once was and based off the few panels about house visits it seems like the Seme is the main one to visit the Uke's house after that one glimpse of the sister so the Uke really doesn't know what the sister looks like anymore since she now looks like a JPop star.
Gremlin OMG
My head could only come up with: A troll, gremlin, or the girl from grudge. So it decided to just spew out gremlin for what she looked like.
It makes sense for this to be the first thought he has. He's been focussed on bringing fown his horny bar since the very beginning. Ofc, as he already interpreted the girl to be a love interest, he'd feel bad and think he's not enough to satisfy him. He's a really sweet and smart character, you guys needa think about that.