Zastin

Lala's personal bodyguard and the best swordsman of the planet Deviluke. He is currently Assistant Chief to Rito's father who is a manga writer due to an incident caused by Lala. Despite his skill with a sword, he has a horrible sense of direction, resulting in him being constantly lost (another running gag in the series).

In To LOVE-Ru Darkness, he now works as a mangaka.

(Source Wikipedia)