Masahiro Yamamoto

Masahiro Yamamoto (山本 昌宏) is a Gate.

He is a soon to be father who was attacked by the Phantom Arachne while purchasing baby items for his pregnant wife Aya Yamamoto (山本 亜矢). He is later held at that Omokagedō for protection after knowing his identity as a Gate. However, he is distraught as he cannot get in contact with his wife and Haruto reports that there is no sign of her being home. Nitoh and the others then decide to search for her, to which Yamamoto begs to take him along with them even though it will risk his safety. Aya was later found by Arachne, until Kamen Rider Beast, intervenes to protect her from the Phantom. During this, Medusa takes the advantage of Kamen Rider Beast being too distracted by the Phantom and fires an energy ball toward Aya which seemingly kills her. Seeing this causes Yamamoto to fall into despair and begins transforming into a Phantom, until it is revealed that Haruto used the Defend Ring in just the nick of time to protect her. Upon realizing this, he overcomes his despair and suppresses his inner Phantom.

Potrayal
Masahiro Yamamoto is portrayed by Shingo Kawaguchi (川口 真五), who previously portrayed Todoroki/Kamen Rider Todoroki in Kamen Rider Hibiki.