Oarai Mentai Park

Kanefuku, one of Japan's major producers of mentaiko (spicy seasoned pollock roe), runs this free-entry factory and museum complex in the coastal town of Oarai. Glass-walled viewing corridors let you watch the seasoning, aging, and packaging process up close. A tasting corner lets you work through different spice levels before buying, and the shop sells fresh mentaiko at factory prices alongside rice crackers, snacks, and freshly made onigiri. The whole visit takes about an hour, fitting comfortably into a broader Oarai day that might also include the aquarium or Oarai Isosaki Shrine, with its torii gate standing in the sea.