PenPen

The PenPens are penguin hybrid creatures that were featured in the Sega Dreamcast game, Pen Pen Tri-Icelon. Pen Pen Tri-Icelon, like Blue Stinger, is notable for being one of the Dreamcast's North American launch titles, and its insensitive depictions of racial characters.

They appear in Blue Stinger in the Hello Market as mascots for a stamp collecting promotion. You'll be given access to the Hello Market Secret Shop elevator when you've collected all four of them scattered around Hello Market.