Blue Oath is a mobile 3D real-time navy battle RPG game, seeing players command their fleet girls into formations to defeat the enemies. A bond system is also in place for players to send gifts to their favourite girls and essentially marry them in game. It’s pretty much similar to Azur Lane going by those game systems.
Ryza is an SSR unit obtainable from the limited time collaboration gacha. She’s not a ship girl herself, utilizing her alchemical prowess to float on water. Her equipment are event exclusives, so you’ll need to play through it and utilize the alchemy pot to create them. Ryza’s swimsuit outfit will also be available to obtain. That’s not all, as all players also receive a free SSR Myoko to help any new players jumping on board to cruise through the event. Puns not intended.
Atelier Ryza 2: Lost Legends and the Secret Fairy launched 25 January 2021, if you just want more of the featured cute girl rather than play through a gacha to get her, you have the option to put the money towards a console game instead.