>>538330717
2 backline red dealers (all 3 Hinas, Mutsuki, Aru, whoever else)
Koharu to heal your tank
Your tank with light (red) armor like Eimi
Mari+Kotama

Start with buffing your dealers+koharu with Kotama. Shield your tank with Mari to remove debuff. Throw Koharu bomb at your tank + Rei if she's low hp, otherwise use dealer EX if it allows for more damage. Repeat until complete. I think it should be possible to achieve the 100 second challenge with some malding, if you want that.