Masahiro Yamamoto (山本 昌宏 Yamamoto Masahiro) is the Green-colored Kamen Rider Mage (仮面ライダーメイジ Kamen Raidā Meiji). He is a father who was attacked by the Phantom Arachne while purchasing baby items for his pregnant wife Aya Yamamoto (山本 亜矢 Yamamoto Aya).
Masahiro is first seen at a bargain market buying some groceries, but then some Ghouls and a Phantom comes to find a certain gate, which is later revealed to be him. Before the Phantom could attack him though, he is saved by the Wizards. Shattered Memory 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. Wiseman's Truth
Masahiro was soon brainwashed and while Fueki and Haruto were talking, Fueki introduces Masahiro as the fourth wizard. The Philosopher's Stone (episode) Masahiro transforms. Masahiro then attacks Haruto, forcing him to transform into Kamen Rider Wizard Flame Style. Fueki boasts that Mage is already as powerful as Flame Dragon, forcing Haruto to switch styles. Despite this, Haruto is defeated. Masahiro is later seen during the Sabbath, used as a pillar to form a Magic Circle to give mana to Koyomi until it was stopped by Beast whom recently cost his power to free Chimera out, as well as freeing him and Yuzuru. The Beginning of the Sabbath After being freed, Masahiro decided not to get involved with a Rider's problems against Fueki and the Phantom's reign, thus decided to watch over his family due to being a magician is like a curse to him. The Important Thing is...
Despite not wanting to get involved with the Riders to stop Gremlin's reign. His family encouraged him to go on and protect anyone whose in danger, as he later joined the riders to stop Gremlin. After the final battle, his son was born.
Sengoku Movie Battle
Masahiro, along with Yuzuru and Mayu arrive to protect Rinko, Kizaki, and Kosuke from the copies of Phantom Carbuncle, However, the Mages were overpowered by the appearance of Phantom Ogre as a result having them critically wounded. However, the three are not dead, as mentioned by Rinko in conversation.