Cousin and adoptive brother to Amalla and Kaolla Su, Lamba Lu is the current King of the Kingdom of Molmol and Kaolla's beloved "Big Brother".
Having made a childhood promise to marry Kaolla, Lamba encourages her to grow up so that they can wed, however, this puts Kaolla at odds between her wish to grow up and marry him and staying a child and continuing to have fun.
Lamba Lu looks almost exactly like Keitaro; the only differences are that he is more tanned than Keitaro, has darker hair and dark green eyes, and is noticeably taller and well-built. Unlike Keitaro, however, Lamba Lu is very calm, collected, and not at all clumsy or awkward. Also in contrast to Keitaro, Lamba possesses a very duty-oriented attitude, a marked difference to Keitaro's idealistic nature.
When the crown king of Molmol passed away he was succeeded by Lamba Lu's father who adopted the previous king's daughters, Amalla Su and Kaolla Su, into his family.
Growing up as siblings, Lamba at one time promised Kaolla that he would marry her, however, not wishing to take on the responsibilities of her royal station, Kaolla ran away to eventually live at the Hinata House in Japan.
When it came time to serve his term in the military, Lamba Lu arrived at Hinata House to carry out his promise and marry Kaolla; to ensure that a royal would remain in Molmol during his term. Amalla also appears and assists her king in convincing Kaolla to marry. When he realises that Kaolla only sees him as a brother, it is eventaully revealed that Amalla herself nurses feelings for Lamba and, on Kaolla's behest, Lamba apologises to her for his lack of attention.
It is implied that, following their return to Molmol, Amalla and Lamba are wed.
Lamba has one theme from the Love Hina anime series, "Theme of Ranba", which is available in the Love Hina Original Sound File soundtrack.
Love Hina (manga)
While Lamba Lu does not appear explicitly in the manga, in volume 14, Keitaro receives a letter from Lamba Lu inviting the former-ronin to take part in a joint research project between Tokyo University and the University of Molmol on the rediscovery of the Todai Ruins.
Lamba is also mentioned at various points throughout the manga as Kaolla's beloved "Big Brother". At one point it is revealed that he writes to her weekly, however, at one point he missed writing to her for one week due to a toothache.