Description
Riamu Yumemi is a 19-year-old idol with 346 Production. She stands 149 cm tall with blood type AB, light pink hair featuring teal underneath styled in playful buns and colorful accessories, and Barbie pink eyes. Her three sizes are "Huge-Average-Probably Average," with soft pink as her theme color and Passion as her idol type.

Her personality reflects the Menhera subculture, marked by neurotic contradictions, extreme emotional swings, and low self-esteem. She craves attention, frequently using the phrase "yamu" ("I'm so sick") and openly expressing loneliness, depression, and self-deprecation. Riamu questions her worth beyond being "a bit cute" and having large breasts, which she does not view positively. Despite these struggles, she demonstrates resilience by consistently attending idol lessons and never giving up.

An avid social media user, especially Twitter, she incorporates internet slang into her everyday speech, often leading to negative online reactions. She distrusts idol otaku who support multiple idols ("daredemo daisuki" or DD types), preferring fans who attend events in person and offer undivided attention. Riamu openly states that causing controversy is acceptable if it gains attention and sales, yet simultaneously fears being hated and pleads for kindness from fans. Her Valentine's Day 2019 dialogue reveals an expectation of eventual rejection and a desire to accumulate as much love as possible beforehand.

She became an idol to drop out of college, believing her life had reached a dead end. A producer discovered her at underground idol shows passionately defending an unpopular idol ("A-chan") while harshly criticizing a popular one ("Mii-chan"). Initially rejecting the offer with self-loathing, she agreed after the producer framed her potential as a "star of controversy," subsequently addressing him as "P-sama."

Her hobbies include composing poems late at night—often described as suggestive—and attending idol events and concerts. She is from "a kind world," a detail shared with other characters. Riamu is close friends with Akira Sunazuka and Akari Tsujino, forming the unit #UNICUS. She also interacts with Anzu Futaba and Kirari Moroboshi, such as when attempting to skip classes.