Muga Iori

He seems to have extensive knowledge of European history. He is a butler of Momiji Ooka, a Kyoto high school student.

Muga is a loyal butler of Momiji, who vows to do his best to support her and her romantic endeavor with Heiji Hattori. He is confident that Heiji's primary love interest, Kazuha, won't be an obstacle for Momiji. Momiji relies on Muga for second opinions. For instance, she asks Muga's opinion on Heiji and even sent him to Tokyo so that Muga could see him with his own eyes; Muga approves of Heiji as the choice for her future partner.

Muga is also analytic and careful about planning for Momiji, making him a trustworthy butler. During the first encounter with Heiji and Conan where he fell under suspicion of a murder at the Cafe Poirot, Muga easily improvised believable answers for Conan, Heiji, and the police's questions. Muga is apparently also stealthy because Conan and Heiji "could not feel his presence" and even the police didn't notice when he later leaves the crime scene.

(Source: Detective Conan Wiki)