Shijima is a Reason, a powerful inner philosophy that encompasses a set of natural laws, based on stillness and oneness, influenced by Buddhism and the concept of Nirvana. It is a world of perfect harmony, where there is no 'self' whatsoever, and no passion to cause dissent, conflict and destruction. Individuality is eradicated, and replaced with a collective inner peace where everyone is equal to a god, all working together as cogs in the giant, stable machine that is the Universe. This Reason is most closely associated with the Law alignment of previous Shin Megami Tensei games.
His dream is a world of silence, where the dangerous passion of man is neutralized, and everyone is at one with the world: this, he calls the Reason of Shijima.
One of the eight devils of Kimon from the kick ass animé movie Ninja Scroll. Shijima could've been a much cooler character if he had been in the movie longer. Shijima has a wicked projectile claw, can hide himself inside of shadows, and apparently take control of women by fingering them.
Shijima takes control of Kagero's body by fingering her tasty pussy.