It's not the first time I see a mention of Chen liking bonito flakes in a fan comic. Is that canon?
Not that I'm aware.
Bonito is made of tuna, though, and apparently a rare example of a human food also sold as a cat treat, so that's probably the basis.
...Don't take it the wrong way, Ran.Cooking for DummiesCooking 4-komaMeooow
Meow meowSo good! Ran-sama's food is always so good!Hahaha, really? Thank you, Chen~Almost as goodTasty!Chen just reeeeally loves bonito flakes...as bonito flakes on rice!