Yabuki Eishirou (夜吹 英士郎), also known as Eishirou (影四郎), is a student of Seidoukan Academy. He is also a member of the Kageboshi. He also worked freelance until Claudia Enfield forced him to be her personal spy.
Eishirou is described as being lean and a head taller than Ayato. He also has a noticeable scar on his left cheek. Under the uniform jacket of Seidoukan Academy, he wears a green hoodie and gray trousers. Eishirou has light brown hair that is almost messy in appearance.
Eishirou is very cheerful and outgoing to those around him, but can turn very serious.
Genestellar (星脈世代): As a Genestellar, Eishirou has enhanced physical ability and an aura known as prana.
Eishirou and Ayato are good friends and roommates, with the former acting as the latter's informant (usually in exchange for food).
- Eishirou has access to a lot of classified information due to being member of the Kageboshi. His job at the First Newspaper Club disguises his other, more clandestine activities.
- According to Lester, Eishirou apparently has a girlfriend named Mikizawa Midori (水城澤 翠), who is the head of the First Newspaper Club which he is a member of. Randy had witnessed her giving Eishirou a hand knitted sweater as a Christmas present the year before.