A magician's tool. Marisa Kirisame uses one which was made by Rinnosuke Morichika.
A Mini Hakkero acts as an arcane focus that adds a +2 to the user's spellcasting modifier. Additionally, spells cast of 1st level or below using it do not require or consume any spell slots. For spells of 8th level or below, if they are cast using the material components, and a Magic Mushroom Mix is used as well, casting that spell does not require or consume a spell slot.
A Magic Mushroom Mix is made up of magic mushrooms, typically found within the Forest of Magic. These ingredients must be mixed over the course of 1 hour. At the end of this hour, it creates 1 Magic Mushroom Mix, which is stored in a small jar.
A substitute for Magic Mushroom Mix may be used at the DM's discretion.