I have got Summer clothes from Asters too . I d infer its Crab too.
So the event is fair , New players could just go kill Asters. Stronger players would stick on seals because seals give decent exp and drop coats[1] too (I got 3 of those while hunting summer clothes) From what I see about seals , The glass bead drop is disabled and instead you get summer clothes. SO the drop rate should be 3.6% ? Amirite?