Itbyoshi

Itsbyoshi is a biscuit brand,  likely parodying the real-life equivalent,  Skittles.

The name is a clear reference to Itsbyoshi, a district in Karakura.

Its existence is evidenced by one of the possible messages that appear after doing /feed or /eat.

"You grab a pack of Itsbyoshi biscuits from your backpack. You enjoy their chocolate and biscuit flavor."