Outside of Gaki no Tsukai, he has released two books, a CD single of his signature "Yamasaki Ichi-ban!" song, and has appeared in several Yoshimoto Kogyo compilations and DVD releases.
Suberu literally means “to slip”, but in owarai lingo, “subetta” refers to a joke or gag that fails to grab any laughs or reaction. (Kyara, short for kyarakuta or character.) Yamasaki’s persona on the show (and in the owarai community in general) is of the unfunny underdog who tries very hard to be funny, but fails. His failure is always accentuated by a snide tsukkomi remark from one of the other members of the show. Though his jokes may be amusing, members will intentionally stifle their laughter to satisfy the running gag.
(Ijimeru, to bully or pick on someone.) Of all the members of Gaki no Tsukai, Yamasaki takes the most physical abuse. The entire series, “Yamasaki Vs. Moriman”, is based around a series of bizarre wrestling matches in which Yamasaki always loses to the larger and powerful Ōshima from the all-female comedy trio, Morisanchū. The content of the matches changes with each battle, but past matches have found the two tossing hot cooking oil at one another, trying to force each other into a tub of blue slime, and whacking one another with thick burdock roots.
During Endō’s “Chiaki Audition” (in which he attempted to find a replacement for Chiaki, his ex-wife), Yamasaki was selected as the victim by all but one of the women when Endō asked the women to demonstrate their slapping ability.
Every year since 2007 during the “No Laughing” New Year's Specials, Yamasaki inevitably comes face to face with an irate Masahiro Chono; a former pro-wrestler, and is slapped with surprising force.
Yamasaki is the most musically apt member of the five, occasionally demonstrating his ability to compose, sing, and play the piano on the show. His own series, “Yamasaki Producer” demonstrates his ability to compose songs of many different genres while having the other cast members, and occasionally outsiders, perform them.
Once a smoker, he quit smoking in 2004.
Yamasaki is married. He and his wife Aya have two daughters named Momo and Rara. His wife once appeared in a “500 Questions” episode while he sat beside her.
He, like the other members, changes his hairstyle almost yearly (with the exception of Matsumoto) but often returns to his trademark puffy-bowl-cut.
Matsumoto along with other staff members occasionally refer to him as “tottsuan-bouya”, which describes someone who is an adult but has a youthful face.