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This article is archived. It is considered no longer relevant in-game, and the information inside this article is taken from a very outdated version of the game, or from LINE Cookie Run.
A Piece of Rainbow's End is a C-grade treasure. It is obtained by upgrading the pet Rainbow's End to Lv. 8.
With upgrades your pet will get 1.5-2.5x bigger in Bonus Time.
It longs to reunite with Rainbow's End, looking for it each Bonus Time.