Not just 4*, but also 3* and below, too. It especially makes me cry on caster class.
I downloaded the NA version since I'm demon-whispering my friends to play this game. And I was surprised to see Caster go PEW! PEWPEW! PEW! *charge* PEWPEWPEW.
She's on my roster in JP, and I love her animation especially Extra attack. Though I wish they give an option to use higher quality assets since zooming in on Rule Breaker is kinda jarring.
It's kinda sad when Kiyohime is still on pewpew and the way to get better animation is... swimwear gacha. I currently don't think it's worth spending money in this game due the non-guaranteed 4* (less about not getting what I want, but more about going home with nothing), unless it's a fukubukuro, or pickup of a something you want/really OP, or swimwear gacha (less about swimsuit, more about different/better animation).
So far, Cat is the best My Room servant I have every seen.
I wish they renew her animation. And/or buff her NP. Out of all the self-stun, the benefits are far too situational.