|Race||Reikon Kyuuban (Elder)|
|Affiliation|| Katsumi Scarlet|
|Occupation||Co-Leader of the Reikon Kyuuban Army|
|Base of Operations||World of the Living|
|Education||Centuries of Knowledge|
|Release Name||Revelation (Bakuro, ばくろ)|
"Hardly anyone has heard Isshuku speak sans me; all he did in anyone else's presence were mere gestures. And cause of that, many had wondered how he could lead armies without a single word. Have you ever seen Isshuku outside that thing? Many had also believed that there was no man underneath that armour, just an earth-bound spirit."
Isshuku (いっしゅく, literally meaning Armoured Warrior), better known by his official title of Sword Saint of Blood (血の剣聖, Chi no Kensei) was part of an ancient and powerful race of elusive spiritual entities commonly referred to as the Reikon Kyuuban.