Tsuruko Aoyama is Motoko Aoyama's sister. She appears in Episode 25 of the anime.
Tsuruko Aoyama is Motoko Aoyama's older sister and the one currently entrusted with the keeping of their family's Shinmei-ryu tradition. She is not active in running the school, having abandoned the life of the sword for marriage and it is her duty to hand the school over to Motoko's care when the time comes. Motoko had fled from the family's dojo due to her disappointment in her sister committing to marriage instead of the ways of the sword.
Tsuruko was created as a supporting character for Ken Akamatsu's Love Hina manga series. There is no information known about her character's design during development of the series. Tsuruko appeared in episode 25 of the Love Hina anime, being voiced by Miki Nagasawa in Japanese and Philece Sampler in English.
Tsuruko stands at 180 centimeters tall (6 feet even), with her three-sizes being 90 cm for bust, 54 cm for waist and 85 cm for hips. She has long black hair that she ties into a ponytail and brown eyes. She is dressed in similar traditional Japanese robes as Motoko and normally carries around her pet crane, Shippu, with her. Tsuruko is 28 years old during her first appearance in the series.
According to an interview from Ken Akamatsu, Tsuruko is not known to wear panties as she opts instead to either "go commando" or wear a fundoshi loincloth.
Tsuruko has a somewhat eccentric personality, yet possesses similar traits as Motoko in following traditional Japanese morals due to their upbringing. She is much more oblivious than Motoko to the ways of the outside world thanks to her sheltered existence. While supportive of whatever Motoko's path of life will be, Tsuruko has a low tolerance for lying and is prone to attacking her sister if she suspects that she is being lied to. She can be difficult to sway in her beliefs of what is best for Motoko once she commits her mind to it, but is devoted to wanting Motoko to live a good life.
Tsuruko is a formidable practitioner of her family's Shinmei-ryu sword style, being among the strongest warriors within her clan's history. Her skill with the sword is such where Motoko has an inferiority complex in thinking she can not surpass Tsuruko. But the older sister believes that Motoko has the potential to surpass her.
Tsuruko first made her appearance in the series to take Motoko back to the family dojo so she could inherit the family's business. Not being ready to return though, Motoko would lie to Tsuruko over choosing to commit to marry Keitaro. Learning of the lie, Tsuruko would lash out at her younger sister by beating her in battle and disowning her. Motoko and Keitaro would later seek out Tsuruko to challenge her in a match to reclaim Motoko's status within the Aoyama clan. As the fight took place, Naru would wind up being cursed by the Hina Blade and Tsuruko would wind up being incapacitated from having her energy drained by Naru. When Motoko succeeded in sealing the Hina Blade's power, Tsuruko would allow her to be part of the Aoyama clan again and departed shortly afterward.
Tsuruko later returned to Hinata Inn a year later under the assumption that Motoko had made it into Tokyo University, unaware that her sister had failed the entrance exams to enroll. While Motoko tried to play up the ruse of making it into Toudai, Tsuruko eventually caught on to the deception and beaten her younger sister in similar fashion to the last time she was lied to. While Motoko sought to sever all ties with the outside world and become a nun upon dealing with this, Keitaro persuaded her not to give up on her dreams and try making it into Toudai again. Motoko would confront her sister a second time in battle, finally defeating Tsuruko in combat while confessing her feelings to Keitaro. Content with seeing Motoko's progress, Tsuruko gave her younger sister her blessings and gave her ownership of Shippu before leaving the inn once again.