A second-year highschool student. Shiori rode on Kai's bike and ended up in an accident, which left her amnesiac when she woke up. Now she's trying to live her life any way she can and maybe even find 'herself' again.
- Alpha Bitch: She is implied to have been one prior to the accident and pretty infamous for her attitude in school.
- Amnesiac Hero: The main plot, after all.
- BrotherSister Incest: Shiori falls in love with Akio after her accident, still not able to see him as a brother.
- Hair of Gold, Heart of Gold: Subverted with her personality prior to the accident. Played straight with the amnesiac Shiori, who is trying to find herself and is overall nice.
- In-Series Nickname: Shi-chan. Kai initially calls her #2 to note a difference between her pre- and post-accident self, but eventually stops.
- Jerk with a Heart of Gold: According to Ono, the previous Shiori may have come across as a snotty bitch at times, but did seem to do small things that implied her to be nicer.
- O.O.C. Is Serious Business: Everyone's reaction to Shiori, in general. Mostly because she is acting the complete opposite of what she used to be.
- Stage Names: When she decides to do some modelling work, Shiori wants to use a fictional name and the studio gives her the name 'Ayumu Kurata'.
A late-bloomer in college and the eldest of the Kikukawa siblings.
- Beware the Nice Ones: He's overall a very sweet and kind person, but when he does get angered - especially when it comes to insulting his family - he can be quite scary.
- In-Series Nickname: A-chan.
- It's All My Fault: He feels it's his fault that his parents' marriage failed because his father brought him into the household and his stepmother did not agree with it.
- Missing Mom: His mother abandoned the family when he was 10. That was his stepmother, actually. His real mother died in a car accident when he was 9 years old.
- Nice Guy: There is no other description for this sweetheart.
- Real Men Wear Pink: After his mom walked out when he was about 10, Akio has taken over majority of the household chores and continues to do so, often making bento for his sisters.
- Thicker Than Water: His entire stance on why he is so lenient with Shiori's moods. He thinks that family should stick together and not be separated.
An introverted child that tends to ignore Shiori because of a strained relationship.
- Brutally Honest: She doesn't talk much, especially to Shiori. When she does, though, she won't sugarcoat her words.
- In-Series Nickname: Maa-chan.
- Locked Out of the Loop: She was never told that she is merely the half-sister of Shiori and Akio.
A childhood friend of Akio's. She moved to Tokyo to pursue a career as a voice actress. However, she has returned to her hometown to take care of her mother's injuries.
She didn't have a good relationship with Shiori.
- Bitch in Sheep's Clothing: The pre-amnesiac Shiori definitely saw Mizuki as this.
- Childhood Friend Romance: She and Akio went to the same elementary and middle school, but began to drift apart during highschool. Mizuki eventually returns home and they start a relationship.
Shiori's kouhai who recently became her boyfriend.
- Delinquent Hair: His blond hair is geled back and immediately makes people see him as a Yankee. Kai says his hair is modeled after James Dean.
- Love at First Sight: He says that's how he fell for the first Shiori.
- Love Epiphany: During a trip to the beach with Shiori and her siblings, Kai realizes that he has fallen in love with the 'second' Shiori.