A few choices at a local supermarket

Baby eels and, on the left, even younger babies.

Below, bora. Above, bora eyes.

Baby octopus.

Pachinko -- a kind of tsukudani -- wakame (one of the commonest sea vegetables here) boiled in soy sauce.

Iwashi (sardines) -- sun-dried, in this case.

Hijiki Wakame

Squid

Hamachi (very cheap, very young)

Just what they look like -- I forget what they're called.