アニメ第110話で初登場。大山砂夫は素直な性格のままマジメなサラリーマンに成長した砂夫。素直さがあふれる完璧なおじぎには、相手も思わず腰が低くなる（妖怪大辞典より）。むりだ城も初登場ですが、図案はもうＵＰしていました。
図案はこちら
Oyamasunao makes his first appearance in episode 110 of the anime. Oyamasunao is a member of the Heartful Clan and is a powered up version of Sunao. The honesty or frankness that exudes from this yokai will make those around him more docile. The origin of the name is unclear. Sunao is a play on 「砂」’suna‘ which means ‘sand’ and 「素直」’sunao‘ which means ‘honest’ or ‘frank.’ The Oyama part of his name may come from the location, Oyamamori, where he appears.
サラリーマンに成長した砂夫 大山砂夫 妖怪ウォッチアイロンビーズの図案
