Asumu Adachi

Asumu Adachi (安達 明日夢 Adachi Asumu) is the main character of Kamen Rider Hibiki. For a long time, he was called "boy" by Hibiki, as he was his apprentice. By the end of the season, Hibiki called him by his real name.

History
Asumu met Hibiki on the way to the memorial service at Yakushima Island before his high school entrance exam. Asumu met Hibiki on a cruise ship to Yakushima Island where he saved a young boy from falling off the ship. On the island, they meet once again before parting ways. Asumu later left his family and traveled by car into the mountains for sightseeing, only to be attacked by Tsuchigumo. Hibiki saves Asumu but afterwards, he saw Hibiki transform into an oni and he was interested in Hibiki ever since. But, after the incident, Asumu had little confidence in passing his exams to get into Jonan High and often seeked advice from Hibiki. After graduating from East Shibamata Junior High School, he enrolled in Jonan High School. He was placed in the same class as Hitomi Mochida and Akira Amami.

He would come to know the secret of the "Takeshi", because Hibiki said he is not willing to disciple, and did not have the feeling that he could after thinking he could do something else, "Tachibana" he only work part-time in the days with no activity.

He had begun training with the introduction of Kyousuke Kiriya, who also wanted to be an Oni. He finally succeeded in apprenticeship under Hibiki. Hibiki had them compete with each other to decide which of them Hibiki would take under his wing. Becoming an Oni can only be learned through training with Hibiki, defeating the Makamou.

Eventually, Asumu realized that being an Oni was not for him. He also quit his part-time job at Tachibana, aiming to be a doctor.

After that, he had communication with Takeshi, Only to reunite with two Oni (Kyousuke and Hibiki) a year later. He was training to be a doctor with knowledge of the courage and training obtained when he was an apprentice. He was able to reconcile with Kyousuke finally, a new teacher-student relationship in the rest of his life with Hibiki.

Kamen Rider Hibiki & The Seven Senki
He was saved by Hibiki when they faced a Makamou which causes Hibiki being injured. This leads Asumu in reading the book that contains the history of the said Makamou and entangled with the history of TAKESHI and the Oni. Learning that his meeting with the Oni is no mere coincidence.