Housekishou Richard-shi no Nazo Kantei

Second-year Kasaba University student Nakata Seigi rescues a foreigner being harassed by drunks. Wavy blond hair, blue eyes, and clear skin. The man who speaks unfaltering Japanese is Richard, a very competent jeweler with customers both domestic and international. Thanked by Richard for being a "hero of justice," Seigi hires Richard to valuate a memento from his late grandmother, a pink sapphire ring. Through Richard, the mystery hidden in the ring is eventually revealed...

Seigi begins working at "Jewelry Etranger." Richard tells him "you will exhibit no prejudice, nor speak in a discriminatory manner," but fails to understand his intention. One day, Akashi Mami comes to get a ruby valuated with the strange request to determine if the gemstone has been heated or not. Mami's brooding expression reminds Seigi of his grandmother, and he is curious. Meanwhile, Mami's troubled fiancee Homura Takashi arrives at the store...

A small customer arrives at Etranger: second-year grade school student Kasaka Hajime. Hajime asks for a gemstone like the one he has and pulls an unset Cat's Eye out of his bag. Seigi is surprised and attempts to question Hajime about his situation, but Hajime obstinately refuses to speak to Seigi, who treats him like a child. Meanwhile, Hajime slowly begins to open his heart to Richard, who treats him like a customer...

Yamamoto arrives looking for a garnet for her engagement ring. Seigi feels positively about Yamamoto who has chosen a garnet rather than the standard diamond. However, when Yamamoto returns to the store, she seems to provoke Richard by stating that beauty is an advantage. Richard goes on to gently unravel the feeling sealed deep inside Yamamoto's heart...

Seigi runs into his middle school hero and senpai on the street but how has time changed him?

Seigi accidentally stumbles on a ring of jeweler counterfeiters, and Richard involves himself.

Seigi accompanies Richard to his first auction where they run into a man from Richard's past.

Seigi's pursuit of Tanimoto-san is thrown into crisis when she announces she has an arranged marriage meeting.

One month has passed since Richard`s disappearance, and it`s now autumn. Seigi asks Richard`s mentor Saul who has appeared at Etranger about his whereabouts, and in return Seigi is asked why he wants to see Richard. However, Seigi searches his own feelings and decides what he will do when he sees Richard and heads to London alone. On the way there, he meets a man named Jeffrey claiming to be a relative of Richard`s.

Working off of the hint Richard left for him, Seigi heads to the lapis lazuli exhibit at the British Museum. There he finds Richard disguised as a woman. While carefully watching their surroundings, Seigi and Richard flee from the scene. Richard attempts to send Seigi back to Japan, but Seigi refuses to leave until they talk, and the two disagree. When the past Richard had kept secret is revealed, how will they choose to act.

One winter day after Seigi and Richard have returned to their normal lives, Seigi helps an elderly woman named Chieko carry her bags. He is served pudding at her house as thanks, where he finds a photo taken in England and a copy of Les Miserables. Seigi recalls the governess Richard described to him and asks Chieko about it, but Chieko`s expression is dark.

Seigi`s father Shimeno Hisashi appears before him. Shimeno divorced Hiromi when Seigi was in grade school and has approached him now that he`s grown. Though Seigi drives him off, Shimeno begins appearing everywhere Seigi goes. Not wanting to cause trouble for Richard or anyone else around him, Seigi tells Richard he wants to quit working at Etranger while hiding the reason from him...