Maybe she's under the weather ? I don't know cos right now I heard it's very hot in Japan & I have friends who flew in from USA + Serbia who're saying the same thing in that they're melting literally
Usually for this type of joint artistes related concerts , it's not an easy thing to do . And I know what it means when the tension is all over the place as it's very rare you will like all the artistes that performed with 1 main star (Kuu) under 1 roof
Hopefully Kuu will take better care of her health before she perform at a-nation stadium fes. later on this month as it's not the norm for her not to deliver vocally :x