In the world of Bincho-tan, Chiku-rin is the energetic and cheerful younger sister of Chiku-tan. She is a young girl who shares a close bond with her older sister, often following her lead and imitating her actions, which highlights an admiring and playful dynamic between the two.

Chiku-rin is presented as a spirited and healthy child, full of the lively curiosity typical of a young sibling. Her personality shines through in the daily activities she shares with her sister, whether they are working, running errands, or enjoying festivals together. She is a constant companion to Chiku-tan, and their relationship is central to her role in the story, as they live together in an old house with their grandfather. One of the notable events associated with her is her birthday, which is on August 6th.

Her role is primarily that of a supporting character, whose presence adds to the warmth and gentle humor of the series. She participates in the simple, slice-of-life adventures that define the narrative, such as attending a festival, playing in the snow, or helping with seasonal chores like making mochi for the New Year. Through these experiences, Chiku-rin contributes to the heartwarming atmosphere, embodying the uncomplicated joy and close family ties that are a key part of her world. Her persistent cheerfulness and her habit of copying her sister make her a notable and beloved presence.