User blog comment:Koishi-Komeiji/Tsukuyo Amane/@comment-4802891-20191001063021/@comment-24965192-20191001131420

Both sisters are raised in completely different backgrounds. They were separated from birth and their family also split. Tsukuyo went with the Akizuki family while Tsukasa stayed as an Amane. Neither knew of the other's existence until just before both of them became magical girls. Before this, they thought they other was their doppelganger.

In contrast to Tsukuyo's mellow and disciplined personality, Tsukasa is more wild and carefree, which Tsukuyo does not appreciate. In turn, Tsukasa fires at Tsukuyo's over-formality as being unnatural and almost robot-like. So they both pretty much disliked each other and even going so far as declaring that they weren't sisters in the first place.

Yeah, you pretty much guessed Tsukasa's kit right. There are some connect skills that give specific effects to specific characters which I also incorporate into the skills here. I don't think it's stronger than trait-based buffs since it only works on a single unit in contrast to trait-based buffs which effect an entire group of Servants.

Mysterious indeed.