|This article is about a/an ally in Kamen Rider Fourze.|
Jiro Iseki (井石 二郎 Iseki Jirō) is a friend of Ryusei Sakuta in Subaruboshi High School. Wanting to be like his friend, Jiro gained a Zodiarts Switch but it self-destructed putting him in a critical state.
Jiro looked up to Ryusei as someone very reliable and wanted to be just like him. He went to the extent of using a Zodiarts Switch in order to gain the necessary power to equal Ryusei which severly backfired. After finding out about Ryusei's selfish lengths to save him, Jiro became so distraught he lost the will to live entering a physical trauma.
Before Ryusei's transfer and becoming Kamen Rider Meteor, he and Jiro used to spend a lot of time together and Jiro grew to idolize Ryusei on how reliable he was. Soon he found a Zodiarts Switch and attempted to use it to become a new and better person. Unfortunately, the switch caused a massive explosion while being stuck to him. Jiro was put into a coma severly injured.
In order to save his friend, Ryusei became Kamen Rider Meteor to find the Aries Zodiarts. When the Zodiarts' identity, Tatsumori Yamada, has been found at Subaruboshi; Ryusei was bribed into killing Gentaro in exchange for waking up Jiro. However, even though Yamada kept his word, Jiro was still critically injured and after he heard about what Ryusei had done, Jiro reentered his coma. When Yamada was defeated thanks to the revived Gentaro in the form of Kamen Rider Fourze Cosmic States, Ryusei talks to Jiro and gets his friend into a speedy recovery.