Ryuusuke Yamino

Loki's second son takes the form of a polite, bespectacled boy in his late teens, and serves as his housekeeper, cook, and assistant. He enjoys cooking, cleaning and other domestic activities, and in the anime, he also has an amusing addiction to ordering useless items from mail-order catalogs. His real name is Jormungand, also known as the Midgard serpent, since his true form is that of a giant serpent that encircles the Earth. Loki rescued Yamino from the bottom of the sea by casting a spell on him (thus giving him a human form) so that he could accompany his father on Earth; for this, he is eternally grateful. The revelation of Yamino's true identity occurs earlier in the manga than the anime, and seems to play more of a part in his characterization for the first manga series. He probably wears glasses as a reference to the Indian cobra (眼鏡蛇 meganehebi, or "glasses snake", in Japanese).

(Source: Wikipedia)