Frustrated with her thankless office job, Retsuko—an anthropomorphic 25-year-old red panda—copes with her daily struggles by belting out heavy metal karaoke after work. After five years at the same company, Retsuko's misery causes her to undergo a series of events that put her job in jeopardy, forcing her to shift her relationships with her co-workers and ends up changing her life in unexpected ways.