Second pairing in Zatch Bell between a mamodo and human partner, after Yopopo and Djem.
Wonrei a warrior mamodo, who dream is to become a king who protect everyone in the mamodo world.
Li-en is a girl os a girl with knowledge and skills in an Kung Fu (Chinese martial arts) who grew up with an over protected father Li-Akron who was one of the most known criminal in Hong Kong. Any man she tried to date her father disapproved, and when she does go on a date everytime she mention her father's name they run away.
The two met when Li-en was trying to forget her ex-boyfriend by eating plate after plate of every kind of food she had on the table when Wonrei stopped her. Wonrei was the first one to show sincerity to Li-en for her struggles and the two ended up being teamed up. Wonrei helped Li-en prepared for the mamodo battle, and in return Li-en taught Wonrei Kung Fu combine with his spells that enhanced his punches and kicks, making them a deadly combination.
As they battle together, their feelings for one and the other grew. However Li-en had been getting hurt alot in battle, and Wonrei was getting worried about her safety. Li-Akron (Li-en's father) knew about the battle and knew his daughter was getting hurt in the battles. Li-Akron talked to Wonrei about his concern about Li-en and wanted Wonrei no where near Li-en and Wonrei agreed to it wanting Li-en to be safe. Before he left he told Li-en about him stopping the battle and confessed his feelings.
Li-en met Zatch and Kiyo when her father send her to her grandparent's house in Japan, and Li-en managed to make it to Momochi city where Suzy and Zatch were arguing to Kiyo about him paying more attention to the spellbook than what they were saying (except for in manga instead of Zatch it was Miroshi). Li-en use the moment to to steal Zatch's spellbook to get their attention and to tell them her and Wonrei's story.
Zatch and Kiyo helped reunite Wonrei and Li-en, and encourage them to keep fighting for their goal and encourage Wonrei to protect Li-en in their battles, and in time as Zatch and Kiyo were trying to stop Zabas and Galiont from attacking them (during the time Li-en confessed her feelings). Li-Akron tried to stop them, but Wonrei stayed by Li-en and promising he'll protect her. Li-Akron trust Wonrei's words after Wonrei didn't move when he threaten to strike with his sword. After they were reunited they went back to Japan to stay at Li-en's grandparents.
Li-en and Wonrei reappeared later on with Dr. Riddles and Kiddo during the attack in town where Tia Megumi Kanchome and Folgore were resting and waiting for Zatch Kiyo Ponygon and Sunbeam, since Zatch and Kiyo helped them in the past.
During the time Faudo appeared, Li-en was one of the four victums that were given a curse seal that threatened her life to force Wonrei to help Leo free Faudo even if it means hurting their friends. But the moment Faudo is free they turned sides to help Zatch and his friends to stop Faudo. In Anime Wonrei's book was burned battling Rodueax. In Manga Li-en had Tia and Megumi burn Wonrei's book to protect him from a blast after battling Anko Tintin, but Wonrei use his own power to protect Li-en Tia and Megumi as well.
Even though Li-en and Wonrei were separated they made a promise to one and the other that they will leave a piece of themselves in each others heart, but even though they were seperated they willstill have each other's memories, and an image of a king who will protect everyone.
Wonrei reappeared in the Gold spellbook with his Shin level spell.