Hiro Sunahara

"' Before taking part in the Holy Grail War I was the most feared boy in my school. I used my Magecraft to get what I wanted, I loved being feared and respected by my peers. I thought I was a powerful magus. A magus worthy of being part of the Sunahara family. But in the battle against Tetsuya I discovered that it was all a lie. It wasn't me who was strong, it was the others who were weak. I, in my weakness, pretended to be the best by attacking those who were weaker than me. '"Hiro Sunahara is a Master who participates in the Holy Grail War of Yggdrasil in the First Arc.

Biography
Younger brother of Hisae Sunahara. An amateur magus who participates in the Holy Grail War of Yggdrasil to prove his worth to his family. He's proposed to enter the war by Yukiko Kumahira who initially acts as an ally but then betrays him. He behaves like a bully towards non-practitioners, but is actually a very insecure person who needs to feel on the same level as his sister, who is considered a natural talent and is much more considered by the family.

First Arc
In the First Arc, Hiro is Rider's Master and initially has an alliance with Yukiko who helps him with the summoning and who then takes him to London. The two share the same hotel room and from the beginning Hiro blindly trusts Yukiko treating her like a mentor, which bothers Rider. In the first battle Hiro proves to be very weak as a magus and is easily defeated by Murakawa Tetsuya and Lancer, but is then helped by Harumi and Archer. At first Hiro wishes to team up with Harumi but due to Rider's opposition he decides not to; Rider herself stimulates Hiro to try to be more independent, especially towards Yukiko.

With the support of Rider Hiro finds the strength to oppose Yukiko and also begins to investigate the girl and so discovers that she works for an organization called New Order of Nidhoggr, however Yukiko discovers Hiro and decides to use a spell to enslave him and thus indirectly taking control of Rider so she can use both in the war. Hiro is sent to fight against Clovis and Caster but is defeated and when Yukiko intervenes to kill Clovis, the boy, in a moment of lucidity, attacks Yukiko leaving Clovis the possibility to escape. Yukiko, irritated, then decides to kill Hiro. He's the first victim of the Holy Grail War.

Second Arc
In the Second Arc Hiro is a minor character who knows nothing of the Holy Grail War but who apparently suffers from his father's mistreatment, this can be understood from the way Kazuo Sunahara behaves with his daughter Hisae when he orders her to participate in the Holy Grail War of Yggdrasil.