Hōzen Ōyama operates as Perman No. 4 under the alias Peryan. This 14-year-old Buddhist monk from Osaka is the oldest core Perman member. His Kansai monk background informs his highly pragmatic and resourceful problem-solving style.
Hōzen excels in intelligence and strategic planning, frequently devising unconventional yet effective solutions. His methodical nature is evident when prioritizing tidal pattern analysis over random searches to locate a damaged submarine. His mental fortitude and strong sense of responsibility make him a stabilizing force within the team, particularly when mediating conflicts between Mitsuo (Perman No. 1) and Sumire (Perman No. 3).
A defining ambition drives him to build a large, profitable company in the future. This entrepreneurial focus occasionally surfaces as pragmatic self-interest in dealings with fellow Permans, though he remains fundamentally reliable in assisting them during crises.
As Perman No. 4, his uniform features a distinctive green helmet paired with a dark blue cape and badge. He employs a turquoise blue copy-robot to maintain his secret identity. His narrative role emphasizes providing grounded perspectives and tactical ingenuity that complement the team, especially during complex operations requiring analytical problem-solving over brute force or improvisation.