Armin is a professional "scare hare," for hire to scare people. He came to Sesamstrasse in episode 2421, where he scared Nils as he was trying to put up a new shelf. Rumpel ended up challenging Armin to a scare duel to find out who is better in scaring others. The competition ended up as a draw.

The rabbit puppet has been used in various roles on Sesamstrasse including Reiner Sauberhasi, Hasi Himmelglück, Knut Köffelström and Henry. He was originally used as Preston Rabbit on Sesame Street.