Iwashi is a significant supporting character in the anime Hakumei and Mikochi. He is a male weasel and a skilled carpenter who serves as the senior colleague and primary work partner of the protagonist, Hakumei. He is a member of the Stone Arrow Association, a local carpenters union based in the town of Makinata.

In terms of appearance, Iwashi is typically seen with a towel or bandana wrapped around his head, and he is often depicted smoking. His personality is characterized by a gruff, no-nonsense exterior that conceals a deeply caring and supportive nature. While his face can look fierce, he takes good care of Hakumei, acting as a patient mentor and guide in her carpentry career. Despite his tough demeanor, he is known for his warm personality and has a tsundere-like quality, showing affection through actions rather than words. Iwashi takes great pride in his craftsmanship and is known to be a reliable handyman who often goes above and beyond in his repair and construction jobs.

His primary role in the story is that of a senior carpenter and mentor to Hakumei. He is the one who introduces her to the leadership of the Stone Arrow Association to request her involvement in a significant stone wall repair project. Their relationship progresses from one where Hakumei appears to be his apprentice to that of respected co-workers. Iwashi helps Hakumei navigate the challenges of working under the demanding Chairman, Narai, providing guidance and support as she proves her skills. Beyond his partnership with Hakumei, he works alongside other members of the Stone Arrow Association, including the Vice Chairman, Katen. Within the union, Iwashi is considered highly skilled, particularly in bricklaying, and is said to be second only to Narai in this specific area.