Tumblr 
Bluesky 
TwitterOOO 24 released
Edit: Looks like these drawings are by this guy
Forgot to talk about the guest last week:
The older sister, Sakura Yuumi, is played by Erena. If you watch our subs, she should be somewhat familiar. She's been in:
Kamen Rider Kabuto episode 12
Engine Sentai Go-Onger 34 (Played Saki's older sister)
and Kamen Rider Ryuki Episode Final as Miho's older sister
Add OOO to that, and that's quite a history
The word:
Etai no shirenai 得体の知れない 【えたいのしれない】 (adj-pn) strange, unfamiliar, mysterious, suspicious
Literally means "not knowing the nature of something"