Humans in Type-moon, Path of the Heroic Spirit

Yu Kamiya traveled to the Type-Moon world and awakened a Heroic Spirit Class Card. It allows Yu Kamiya to travel to different eras. As long as he completes the corresponding great deeds and legends, he can be recorded by the Class Card, and uploaded to the quantum recording tape, and transformed into "his own" power. So, Yu Kamiya began his journey as a Heroic Spirit, and the first stop was the Shadow Kingdom located outside the world. ...1994. Yu Kamiya, who graduated from the Shadow Kingdom, was chosen by the Holy Grail and became an ordinary Master. It was originally planned to summon Caster to join the battle, but it turned out that it was his own senior brother Cu Chulainn who was suspected to be Odin's substitute? And the purpose of this "senior brother" of his own to join the battle this time does not seem to be simple... Cu Chulainn: "Junior brother, you go and get rid of King Arthur!" Yu Kamiya: "Ah... I fight King Arthur?! Really...