|“||All we want is to remain by your side. Wherever that may be, as long as you're happy, so as we, Master Loki||”|
—Yamino to Loki
Yamino Ryusuke is a polite, bespectacled boy who serves as Loki's housekeeper, cook, and assistant at Enjaku Detective Agency. He enjoys cooking, cleaning and other domestic activities. It is revealed that he is actually Loki's son and his real name is Jormungand, a serpent.
He appears most commonly in his long black pants, dark blue jacket, black shoes, with thin red ribbon. In his serpent form, Yamino's irises become icy blue and his pupils thinned like that of a snake.
He appears to be a mild-mannered individual who enjoys domestic activities and other 'feminine' activities. Yamino is also meticulous when it comes to things such as cleaning and cooking. He also has an amusing addiction to ordering useless items from mail-order catalogs.
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.
Yamino is first seen when he served tea to Loki. He said that no customer came today but Loki said someone will come. Hearing the door bell, Yamino went and open the door. It was just a fast delivery. They deliver Shimeji, a type of mushroom. Later, he greeted Mayura who come to their mansion and brought her to meet Loki. He sighed that Mayura was the only client on that day but Loki said that he sensed an evil power that she might had picked somewhere.
Yamino used iron sticks that he calls Ghost Collector which he got from the delivery. He said that they can detect any ghost within a ten kilometer radius and assumed that they could detect evil spirits too. Loki questioned him if he really believed that which made him wonder why. Loki said that it was nothing and suddenly the Ghost Collector moved much to their shock. The Ghost Collector brought them to an abandoned site and they saw Mayura trying to search for the doll. Yamino told them that she found the doll in the clock tower and the black cat that snatched it away was also from the clock tower. So she thought that it might bring the doll back there. But when they were nowhere to be found, she searched around the area. Yamino asked Loki why he changed his mind to help her and Loki answered the he just help her because it coincided with their investigation. Suddenly the Ghost Collector gave a strong signal of evil spirits. He dragged Loki along with him.After receiving the sign, he dug the soil saying that he would do anything to Loki. When Loki asked if he found anything, he said he didn’t found it yet. He continued to dig until his shovel hit something; it was a water source. He said to Loki that he found a hot spring but Loki said that the water was cold. They met an old woman that worked in the mansion twenty years ago. When Yamino asked her if there was a talk machine in the doll that's still operating, the old woman was confused saying that thing is ridiculous indicating that there was no machine in that doll. They arrived just in time before a candle holder nearly knocked Mayura down. When they return home, Mayura called him a genius as he cooked a delicious Shimeji. When she said that she would become the helper for the agency, he asked Loki if that was alright. Mayura asked for the second bowl and just like her, Loki also asked the same.
Yamino aka Jormungand is Loki's second son. He enjoys taking care of his father, who wandered in a child form. Yamino is also thankful for his father ever since he was given human form to travel easily, saying that he would do what ever he could to assist. He is very protective of Loki and in private, calls him "Father" in the English Dub and "Chichi" in the original.
Fenrir is Yamino's elder brother, in which he uses the term "big brother" in the English Dub and "nii-san" in the original. In episode 14, Yamino is relieved to see his brother again, however in a different form (one of a black puppy). He is astounded to find out from Fenrir that the unbreakable chain Gleipnir broke, freeing Fenrir. Fenrir is quite rude around Yamino or as long as Loki isn't around. Calling him a bastard and using foul language. around him. Nevertheless the two seem to get along fine.
Hel is Yamino's older sister, who he hardly knows anything about her other than that she is the goddess of the underworld and that he fears her power. It was her doing that Fenrir was freed from the chain, which is shown in episode 14. After Hel died, he asked Loki if she smiled as she passed, signifying that she was finally happy. They are both bespectacled children.
Yamino thinks of Mayura as a friend and finds her amusing while also worrying constantly.
Yamino had fear for Narugami in their first meeting and can tolerate Odin's son to an extent. He was given the nickname "Four-eyes" in English Dub or "megane" in the original. "Megane" is another way of saying "glasses", "me" meaning "eye".
Spica, also known in the manga as Angrbo∂a, a jotun and the mother of Hel, Fenrir, and Jormungand.