A 4th-grade elementary student. Appearance: Black short hair, always covered in bruises or wounds somewhere on her body. She lives in a state of neglect while her mother works at a hostess club. Furthermore, her mother is having an affair with the father of her classmate, Marina Kirazaka. Shizuka's father has already left the home and is absent; her biological father now lives in Tokyo with two other daughters. She is subjected to severe daily physical violence, psychological abuse, and bullying by her classmate Marina. This stems from Marina's misplaced grudge over Shizuka's mother destroying Marina's family through the affair. Her classmates and teachers turn a blind eye to the situation, leaving her isolated and unable to seek help. As a result of enduring this hopeless environment, she shows little emotional expression and remains largely expressionless unless something major happens.

A 4th-grade elementary student. Appearance: Characterized by long blonde hair with a headband exposing her forehead. She wears black long sleeves even in the summer. Personality: At first glance, she appears to be a cheerful and cute girl, but she is deeply warped inside and bullies Shizuka. She is kind to all classmates except Shizuka. Believing that Shizuka's mother is the reason her own family life is falling apart, she targets Shizuka for daily verbal and physical abuse. Her father frequents the hostess club where Shizuka's mother works, which has made Marina's mother hysterical and violent toward Marina.

A 4th-grade elementary student and the class representative in Shizuka's class. Raised in a family of doctors, he has excellent grades. He suffers under the constraints of his "tiger mom" and feels immense stress from an inferiority complex regarding his perfect older brother, Junya. His mother calls him "you" instead of by his name, leading to low self-esteem. Relationship with Shizuka: By staying close to the bullied Shizuka, he seeks unconditional love and a sense of being needed, eventually becoming complicit in Shizuka's sins. He usually wears glasses, but the prescription is wrong, making them almost useless. However, he missed his chance to say anything and has just kept wearing them as they are.

True Identity: An extraterrestrial known as a "Happyian." Purpose: A journey to spread happiness throughout the universe. Verbal Tic: Ends sentences with "-ppi." First person: I (soft, polite). Immediately after landing on Earth, he was saved by Guest while on the verge of starvation. Flappy Ribbon: A ribbon that allows flight. Memory Squeezer: A tool that can erase memories. Recall Ribbon: The ultimate key item that can rewind time. Note: While his tools are used with good intentions, in the face of Earth's harsh realities (bullying, abuse, broken homes), they unintentionally become triggers for disastrous outcomes. Since the concept of bullying, violence, or broken homes does not exist on Planet Happy, he cannot correctly understand human malice or suffering. Lack of Empathy: Even when witnessing horrific situations or violent arguments, he misunderstands them as "having a friendly chat," showing an extreme inability to empathize with complex human emotions.