Basshou

"I believe you're mistaken, Mr. Kuchiki. I do not wish to bring grave harm among the innocence. It's quite the opposite, actually.  I mean to save all innocent souls that have been oppressed by the tyranny of the Gotei 13.  Along with my loyal followers, I will lead Soul Society to a great salvation.  It's as my mentor, Shoyo Tabinin once said; peace is not something that can come naturally to this war torn world.  It must be enforced.  And I will be the enforcer of the new world order.  Together, we will crumble an empire.  Get in our way, and you will also lay dead beneath the rubble."

- Basshou to Ginrei Kuchiki

Basshou is a religious preacher and spiritual guider in the Rukongai District Zaraki. In secret, he is the genius leader of an underground cult with the purpose of overthrowing Soul Society's government. He views the Gotei 13 as nothing more but tyrannical leaders, and wishes to end their leadership once and for all. Making matters worse for the Gotei, he's often allowed to enter Seireitei to speak at Shino Academy, as well as to division members of the Gotei 13 who needs spiritual guidence. This is due to being one of the eldest souls alive in Rukongai, and has connections with the Yamamoto House, one of the four great Houses in Soul Society, a connection that dates back over 7,000 years. This connection, combined with his huge amount of intelligence bult up over his entire long lifetime, made him the perfect person to lead a rebellion; it also happens to be required, as he doesn't possess any great amount of skill or power in any form of the Zankenoski today, unlike his early years.