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The Bear-san Rucksack (Japanese: クマさんリュック) is an item in Densetsu no Starfy 3, found in the Jungle (Stage 5-2). Hirao and Hirarin give it to Starfy after he gives them the Shovel. Starfy, Starly and Moe must give it to Kabasonchou to receive the Title Certificate as well as the Bear-san Pouch Accessory.
According to its item description on the Item List, it is a cute bear rucksack that is only worn on the ear.
"This is a super cute rucksack featuring Mr.Bear! Just by wearing this, you can make anyone look cute!"