Masamune Habutae is a member of the Kura organization, serving on the Wellside team which operates and controls the Mizuhanome System. As the Human Analyst, his duty is to identify and report on individuals appearing within id wells during investigations. He joined the newly established Kura roughly six months before the main series begins.

Habutae is a young man with somewhat long, spiky black hair and brown eyes. He typically wears a black suit, a light pink shirt, and a darker pink tie. For formal events such as a funeral, he dons a darker suit with a white shirt and black tie.

In personality, he carries out his duties with focus and seriousness, much like his Wellside colleagues. He occasionally shows amusement in his work, such as when he was entertained by the detective Sakaido considering an arrest within an id well. Habutae displays self-awareness, noting the advanced and nearly fantastical nature of Kura's technology. Though not as emotionally invested as some coworkers, he demonstrates empathy, often proposing altruistic motives behind id well manifestations and expressing unease when faced with a colleague's abrasive conduct.

The name Masamune can mean "right, proper" and "religion, sect, denomination, main point, origin, essence." His surname, Habutae, means "feather," "two," and "multilayered."

In the sequel manga ID:INVADED #BRAKE-BROKEN, Habutae continues as a supporting character, maintaining his role within Kura as the organization investigates new cases after the events of the original series.