The first purchase contains the following bonus content:

■Kuuta's Travel Tool: Cloud Crest
Equip this item to swap the bag Kuuta carries to one with a cloud pattern!
Fluffy white clouds against an indigo sky make a striking combination.

■Kanna's Kimono: Indigo Fiber
Talk to Kanna, the mysterious girl who lives on Kisejima Island, to change her outfit.
The Indigo Fiber Kimono's intricate pattern is truly a work of art.

More details on the official game page of ONI: Road to be the Mightiest Oni First Purchase Bonus ...