They are inhabited by shulkers and hold loot among the most valuable in the game. In both games, Vegeta appears with his Super Saiyan 2 under the name 'Super Vegeta 2', which focuses on raising the power of ki blasts. For Chaotic Leader Quests, the Fighter you start with is the only eligible unit to become a Winged Horserider unless you create more.
Also, I'm thinking about how to integrate Yjs into the system composed of the former two well. First of, I'd like to say I'm sorry about JinRyuu's passing away.