"Asada is a key character in the Japanese manga ""Haikei... Koroshiya-san to Kekkon Shimashita"". He first appears in the manga as a client who hires the protagonist, a hitman named ""Koroshiya-san"", to find his missing girlfriend.

Asada is a middle-aged man with short black hair and glasses. He is depicted as a serious and reserved person, but also a caring boyfriend who is deeply concerned about his girlfriend's disappearance. As the story progresses, it is revealed that Asada used to be a detective before retiring and becoming a successful businessman.

Asada's relationship with his girlfriend, Ayano, is a central theme in the manga. He explains to Koroshiya-san that they met at a party and quickly fell in love. However, Ayano's sudden disappearance and the mysterious circumstances surrounding it leave Asada feeling helpless and desperate for answers.

As the story unfolds, it is revealed that Ayano's disappearance is linked to a larger criminal organization that Asada had investigated in his previous career as a detective. Asada's past comes back to haunt him, but his dedication and determination to find Ayano motivate him to keep moving forward.

Throughout the manga, Asada plays a crucial role in supporting Koroshiya-san in his investigation, providing insights and leads that help them uncover the truth behind Ayano's disappearance. Asada's intelligence and resourcefulness, honed through years of experience as a detective, prove invaluable to the investigation's success.

Overall, Asada is a complex and compelling character whose love for his girlfriend and dedication to finding her make him a key player in the manga's plot. His past and present intersect in ways that drive the story forward and keep readers engaged until the very end."