Clemene is a mysterious dragon from the Harmony Faction.

Like many of the Harmony dragons, he not only despises humans but also the dragons of the Chaos Faction and swore to eradicate them.

When he follows Llulu to earth and was about to kill her. Kobayashi and Tohru intervene to save her but Clemenne punches Kobayashi who was in his way in spite of the oath that Harmony dragons, while they dislike humans, they don't lay their hands on them in respect. Tohru in anger heavily beats him and wipes his memories clean.

(Source: Kobayashi-san Chi no Maid Dragon Wiki)