I stand corrected. I mistakenly classified her as a limited character due to the odd circumstances of her introduction (in the middle of an event as part of a promotional campaign). Even so, she's a desirable SSR healer that pairs well with Cthulhu and Sol, and waiting those few extra days for her to be introduced overall increases the odds of pulling a strong water SSR. Ryuuou is also very good, but her skills replace rather than supplement 1 each of Nike and Cthulhu's abilities. She's great at providing debuffs for a team that doesn't have them, but not so great at complementing Water's other excellent debuffers.