Three Religions, No Gods
The divine forces of Yamato are the kami, spirits that inhabit various places, creatures, objects and realms. The weakest kami have no power and are barely detectable, while the greatest amongst them are godlike in power (but are not actually gods). Divine magic in Yamato involves communing with the kami to manifest magical effects in the world.
That said, divine magic is rare in Yamato. Legend says that 500 years ago, the great demon Okuroyama rose up and threatened to destroy the land of Yamato. It took all of the great kami standing together to even slow him down. Finally Ameterasu, greatest of the kami and creator of the islands of Yamato, ate her fellow great kami, absorbing their power. She then grappled with the great demon, and commanded Susanoo, the great warrior kami whom she did not eat, to stab both her and the demon with his great spear. The spear pinned Ameterasu and Okuroyama to the ground, but could not slay them. It is said to this day Ameterasu and Susanoo expend all their might simply containing the great demon, preventing him from arising and consuming the earth. It is for this reason that divine magic has become so rare in this day and age.
With that said, you are free to play a divine caster. Just understand that you will be possessed of a truly extraordinary gift, and will be practically unique outside of the Imperial Court.
The official state religion of Yamato is Shinto. Priests venerate the kami and conduct highly formal rituals to commemorate social milestones (such as weddings and funerals) and natural ones (such as solstices and eclipses). Shinto would be considered a lawful religion, emphasizing order (social and natural) and obedience. All Shinto clerics must be of lawful alignment.
The Emperor is the High Priest of the Shinto religion, and conducts many of its most important ceremonies. The nobility and the common folk generally adhere to Shinto teachings..
Followers of the Awakened One, a sage from a far off land, the Wayfarers seek personal enlightenment through meditation and moral action. They have a strong monastic tradition; most of the monks of Yamato come from Wayfarer monastaries. Most Wayfarers are of good alignment, although there are some who are true neutral, who maintain that good, evil, law and chaos are but ripples in the deep ocean of the Way.
Note: a monk who is a Wayfarer may be absolute neutral. This is an exception to the requirement that monks be of lawful alignment.
The Wayfarer tradition is popular amongst the samurai class. It is not particularly rare for common folk to follow the teachings of both Shinto and the Wayfarers (Shinto being more concerned with public life, while the Wayfarers concern themselves more with one’s inner life).
Some say the Wanderers are a splinter sect of the Wayfarers, while others maintain that the Awakened One was himself a Wanderer who split off to form his own tradition. In any case, the Wanderers share with the Wayfarers an emphasis on meditation to achieve enlightenment, but place a greater emphasis on individual freedom (and responsibility) and less on compassion. Wanderer clerics are never lawful; they can be neutral good, chaotic good, absolute neutral, or chaotic neutral.
Note: Wanderers don’t have monastaries, but they do have a tradition of hermits studying martial arts as a path to enlightenment, and passing on their knowledge to worthy students. A Wanderer monk can be of any alignment available to a Wanderer cleric; this is an exception to the requirement that monks be of lawful alignment.
The Wanderers are a small religion in Yamato, but influential due to their collective body of esoteric lore, particularly in the area of alchemy. Their path is also attractive to people who find themselves chafing against the binding structure and hierarchy of Yamato society.