Kaoru Hitachiin  

, 常陸院 馨

Kaoru Hitachiin is a mischievous first-year student who loves to play pranks on his fellow Host Club members, including Haruhi and Tamaki, whom he often refers to as "My Lord." Along with his older identical twin Hikaru, they are known for their devilish behavior and portraying an act of forbidden brotherly love (with Kaoru playing the role of the uke). Unlike Tamaki, the Hitachiin brothers approach customer relations in a calculated manner due to their deep dependence on each other and their reluctance to let others into their world. They share a strong emotional bond formed through their shared childhood experiences and the fact that no one could tell them apart without looking at the parting of their hair (Hikaru's hair parts to the right, while Kaoru's parts to the left). Haruhi has noted that despite being identical twins, Hikaru and Kaoru have distinct personalities. Kaoru is kinder, more mature, and considerate of others compared to Hikaru.