Dan Morihiko

Dan Morihiko is the most famous and respected detective in Japan and one of the central characters of the series.

Biography
Morihiko Dan was born in 1936.

Founder and principal of Dan Detective School (DDS), he is a famous detective who has solved many cases, and is the only private detective in Japan who is licensed to carry a gun.

Morihiko Dan was a former police officer who resigned to open up a private detective company of his own, Dan Detective Company (DDC), the parent company of DDS.

His assistant was a young boy named Satoru Renjo, who soon acted as his partner and protege. Together, they had solved countless crimes and fought many criminals. Among them was Meiosei, a crime organization that acted as a "murder designer," creating a perfect, fool-proof murder plot for their clients. The criminal organization was famously known as their greatest adversary.

Although Meiosei was finally thought to have perished, it wasn't without a cost. Satoru Renjo was killed and Morihiko Dan was forced to be in a wheelchair for the rest of his life.

Years later, his age starts to catch up to him. He soon realizes that his days were numbered, so he decides to open a new, special class called Class Q (stands for Qualified), consisting of several extremely talented students. He would train them, analyze each one of them, and appoint the best student of this class to be his successor.

Personality
Despite being one of the most respected detectives in Japan, Dan still remains humble. He is also not strict when it comes to his students.

Difference between anime and manga
How Kyu met Morihiko Dan is quite the same albeit a few differences (the manga depicts Kinta accompanying Kyu while the anime depicts Megu accompanying Kyu instead).

One of the differences is the ending. While the anime ends abruptly with the seeming demise of Meoisei showing that Morihiko Dan is alive, the manga ends ambiguously. Morihiko Dan either passed away due to his old age or he's simply asleep. That is up to the readers to decide whether he's long gone or not.