>>530502052
He's there to test if you know how the game works yet. If you've got some of the basics down. By the time you know how to play you'll wonder why you ever had trouble with it.

He's a red boss, which means red characters are going to do the most damage here.

Yuuka, Aru, serina, maybe one yellow student since I think the boss spams blue mobs. If you could borrow a Mika it would be over in an instant.

If nothing else you could just roll an overpowered student for bluefest.

>>530376841
With blue tanks you have the option of
>Tsukuyo
>Super Hoshino
>Sports Yuuka
>Natsu

Out of the options you have Natsu is probably the cheapest, but I doubt you can get her that quickly. Purple units and blue units are interchangable due to an efficiency fuck up where they're basically effective in the same places. It only works with purple and blue, but you can use them both on each other's maps