Went today and did not find onigiri without salmon, cod or shrimp
I've seen all of the above (except maybe coffee jelly, but you can buy the mix I believe). However, the premade items seem to vary by day and time, so it can be challenging to get your hands on all of those. Most of the time when we shop, they're already sold out... Unless we go early.
I really can't say because I have never had any of that.
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