After being sold to a traveling circus by her parents with Anzu, Karin was determined to make enough money so that they could return to their family. This meant taking on the role of a parental figure towards Anzu.
On top of possessing skill in the art of acrobatics, she is shown to be compassionate, reserved, and mature.
She loved the people around her deeply and with devotion. Whenever she faced hardships, she was always quick to sacrifice her own happiness for the sake of others.
Sanbou Den Part 1
|“||This hand mirror...will protect me?
— Karin, Sanbou Den Part 1
When their family falls on hard times, seven-year-old Karin and five-year-old Anzu are sold by their parents to a traveling circus in order to pay their debt. Karin thought if they both save enough money their parents will take them back. She spends hours practicing her acrobatics, which inspires a knife-throwing performer, Raimon, who decides to put more time into his training.
Several years pass and the troupe travels to Sairou. Karin witnesses the summoning of Seiryuu at a show and the beast god scares the audience off before they have a chance to pay. The owner of the circus blames Karin and Anzu for taking too long with their performance.
The circus sets up in Kutou and after a show, Raimon asks Karin to meet him in the center of town. She goes to the spot and realizes Raimon is not there. Time passes and she is about to give up when Anzu appears, clearly distressed.
Her younger sister explains that Raimon has been arrested and wrongfully accused of stealing papaya blooms from a shopkeeper.
Karin confronts the owner of the circus who then makes a deal with a wealthy landlord with political influence to release Raimon. In exchange, Raimon will have to confess to the theft and Karin must marry the landlord. When she asks about Anzu, the owner assures that, if she cooperates, her sister will be allowed to leave the circus.
She agrees in tears and the circus owner and landlord take her to see Raimon the next day. She asks him to confess to stealing the flowers but he refuses, believing that she has been bribed. Before they leave the jail, Raimon slips her a beautiful hand mirror and a priceless necklace that he found in the ruins of a temple in Sairou after Seiryuu was summoned. Unbeknownst to them both, they are Byakko and Genbu’s Shinzahos.
But Karin is too distracted to appreciate the gifts, knowing Raimon is doomed if he does not confess, she leaves with a broken heart. When the time comes to say goodbye to Anzu, Karin gives her the necklace she received from Raimon, claiming that he said it would protect her.
Months pass and Karin is locked in a cell when she refuses to consummate her marriage with the landlord. She is told she will only be let out if she agrees to sleep with him but her heart still belongs to Raimon. The days drag on and whenever she feels she is about to give up hope, her hand mirror shows her the face of Raimon.
One night during a heavy rainstorm, the mirror signals her to point it in the guard’s face. White light flashes and the guard falls. Karin escapes through the rain. Sprinting through the Kutou countryside with the landlord’s guards on her heels, she finds herself at the edge of the massive Shouryuu River, its waters raging violently.
In her haste, the mirror slips into the river and Karin dives in after it. She grabs the mirror but struggles to stay above the water. Suddenly, someone lifts her out of the water. Believing it is one of the landlord’s guards, she struggles until she realizes it is just a monk, Chichiri, who introduces himself as Houjun Ri. He takes her to an abandoned hut to dry off. She tells him everything that has happened to her before asking about his past. He tells her but leaves out his role as a Celestial Warrior of Suzaku.
The next morning, Karin wakes up before Chichiri, checks her mirror, and suddenly goes back to bed, wrapping her arms around the monk. When he moves away from her, she admits that she is very doubtful Raimon will come to rescue her so Chichiri can sleep with her. Karin, clutching the mirror, says she wants to marry him and travel around, specifically to Seiryuu's shrine.
Chichiri realizes the mirror is Byakko’s Shinzaho and when he looks into it, he sees a pair of glowing eyes. Tenkou’s eyes. He knocks the mirror out of her hand and she comes to her senses. They decide Karin must not look into it again and that they must find Raimon as soon as possible.
The two go to the jail where Raimon is being held but he is not there. The prison guard is also uncomfortable and reluctant to tell them what happened to Raimon. Karin suspects he has been bribed by the landlord and demands he tells the truth.
The guard reveals that the landlord did not grant Raimon his freedom and he was burned at the stake. Karin is in shock but she notices Chichiri goes into a deep state of concentration as if he was listening to a voice that was not there.
Sanbou Den Part 2
|“||It's all my fault! I wish I could have died with you!
— Karin, Sanbou Den Part 2
At the Kutou jail, Karin is in denial about Raimon’s death. Chichiri tells her that he suspects that Raimon has been reborn and is under the influence of a demon god. He asks for her hand mirror but Karin grows suspicious and asks how he could help Raimon with it. Chichiri reveals himself as a celestial warrior but his symbol on his knee will not appear.
Distrustful of him, Karin points the mirror at him, it flashes a blinding white light and she bolts out of the jail. While running, she considers that Raimon might actually be dead. But all her doubts disappear when she looks into her mirror and finds a sweet image of Raimon smiling back at her.
Rumors begin to circulate that Karin is back in Kutou with a strange man which prompts the landlord to go looking for her. He encounters the circus owner who blackmails him with Raimon’s death for money. When the landlord takes out a dagger, Karin interrupts the exchange.
The landlord is happy she has seemingly come back to him but the two men notice something is off with her. Her hair and robes are disheveled and her eyes gleam in the moonlight. She learns that the circus owner had framed Raimon for the robbery to dispose of him so that he could sell Karin to the landlord for money. Karin takes out the mirror and paralyzes them, prepared to kill them. But Raimon stops her.
Karin runs to him but falls straight through his body. He apologizes that he cannot hold her and she smiles painfully before losing consciousness. Raimon takes the mirror and burns the two men to death.
Raimon carries her to the Seiryuu shrine and confronts Chichiri, Tasuki, and Anzu. He demands that Chichiri retrieve Seiryuu’s Shinzaho or he will slit Karin’s throat. Hearing this, Karin wakes up and begs the monk to let her die with Raimon. Anzu and Tasuki protest but Chichiri enters the shrine and gives the Shinzaho to Raimon.
No longer in need of a hostage, Raimon tries to kick Karin away, but she refuses to budge. A battle ensues but Chichiri remains calm. Karin apologizes for the pain he went through and blames herself for everything. She gives a tearful confession of her love for him.
Raimon becomes overwhelmed and transforms into the kind man he was before. But Tenkou’s power is stronger than expected. Both Raimon and his monkey turn into their corpse-forms and start attacking the group once again. Tasuki pulls out his Tessen and Raimon thanks Karin and tells her he loves her before he turns to ash.
In need of a break, Karin, Tasuki, and Chichiri take Anzu up on her off to create a traveling act in Konan. For their opening show, they return to the spot where she first performed with her sister. Outside the venue, they find young quince and apricot saplings and spread Raimon’s ashes together.
One day, the two warriors disappear. Surprised but not angry, Karin tells Anzu that she can find Tasuki if she wants to, but her little sister wants to stay with her until she matures. Karin stares at the trees and sighs.
- Karin's name means quince, specifically a Chinese quince. The quince tree makes an appearance at the end of the novel symbolically next to an apricot tree, for her sister, Anzu.
- She is the third person Chichiri has saved from a water-related incident. Karin is among would-be-victims Koran Ou from Shouryuu Den and Hiko in his demon-god form in the OVAs.