Kaoru and Hikaru

Hikaru usually sits or stands on the right while Kaoru stands on the left to align perfectly either natural hair parts. Furthermore, their facial expressions give them away: Hikaru's smirk is usually wider and more mischievous, while Kaoru's expression is softer and more pleasant. This can be noticed by sharp and perceptive people.

His hair naturally parts to the left side, and he is entirely left-handed. He also has a notably softer, and gentler voice.

his hair naturally parts to the right side, He is also entirely right-handed. He also struggles to recognize his own emotions, and requires Kaoru or Haruhi to explicitly point out when he is feeling jealous, or lonely.

both are troublemakers, they are twins, in the host club. Hikaru is the dominant, emotionally volatile older twin, while Kaoru is the calmer, more mature, and insightful younger twin.