Super Mario Maker has had a good mix of familiar and lesser known characters in its regular Event Course unlocks, and the next in line is certainly in the latter category.
Having seen the latest video on Nintendo's Japanese channel we had trouble figuring out who it was, so hat tip to Perfectly Nintendo for the details. The cute pixel you can see below is Yuu Ayasaki, voice actress for Super Mario Maker manual guide Mashiko / Mary-o, and also a recognisable star from 3DS title Daigasso! Band Brothers P; that game hasn't made it to the West.
This event course and character land in Japan (and very likely everywhere else too) on 21st March; check them out below.