Head on over to Venus Island to take part in the Nanami's Challenge～Softening Beauty Chapter～ festival.
A swimsuit from the Boss is delivered to Nanami's doorstep. Although flustered at how skimpy it is, Nanami tries it on anyway. Nyotengu and Kanna happen to drop by to hang out, and witness her wearing it.
Collect Silver Midnight Hearts in festivals to exchange for, among other things, the Choco Towel Wrap outfit.
The Trendy Gacha this week can get you the Festival Goldfish outfit for Kanna, or the Starry Night Goldfish outfit for Nyotengu.
There's also the Star Outfit Gacha, which can get you the Midnight Light outfit for Nanami.
The First Butt Battle Festival festival will run until 5th of July 2022.
If you want to participate in this festival, unfortunately DEAD OR ALIVE Xtreme Venus Vacation is still only available in certain regions via Steam, and digital download in Japan.