“High Summer Formal” is a new special costume for Ryza.

It commemorates the fact that “Atelier Ryza: Ever Darkness & the Secret Hideout” and “Atelier Ryza 2: Lost Legends & the Secret Fairy” have exceeded one million units sold worldwide.

Costumes can be changed by selecting "Changing Room" from the diary found on the desk in Ryza's atelier.
Note: For more details please visit the official website: https://www.koeitecmoamerica.com/ryza2/

More details on the official game page of 【Ryza 1 Million Units Celebration】 High Summer Formal ...