Marici (or Marishi-ten in Japan) is a solar deity of light and the heavens and a tutelary deity of the warrior class who is revered in many schools of Buddhism. Her origins are obscure, but she believed to be an amalgamation of Hindu, Iranian and Non-Aryan antecedents dating back 1500 years. Marici is depicted as either a goddess on a lotus, a multi-armed goddess with many weapons on the back of a boar (similar to Durga), a deity riding a fiery chariot of savage boars or a ferocious demon on the back of a boar.
Marishiten in Japan is also believed to be a non-standard member of the Seven Lucky Gods who is largely supplanted by Benzaiten. She is also believed to the consort of Dainichi Nyorai and is the harbinger of Dainichi, associated with the blinding rays and fire of the rising sun, and thus with the power of mirage and invisibility. She is also a part of a group of three deities called the Santen, alongside Benzaiten and Daikokuten.
In China, she is worshiped as both a Taoist and Buddhist deity known as Doumu (Chinese: 斗母元君; pinyin: Dǒumǔ Yuánjūn), the Mother Dipper. Most often she is depicted with three eyes in each of her four faces; with four arms on each side of her body and usually sitting on a lotus or boar. Two of her hands are held together, and the other six hold a sun, a moon, a bell, a golden seal, a bow and a halberd. She remains today as one of the most popular Taoist deities, being the mother of the Nine Emperor Gods, who each represents one of the stars in the Beidou constellation. She is still worshiped at the White Cloud Temple in China and her celebration day is on the 9th day of the 9th month.
Marici appears in the Challenge QuestSamurai School in Nakano, and is found in the area of Nakano in Shinjuku. Worshiped by Samurai of old, she admits that she doesn't find joy in battle, but being worshiped is invigorating for her so she accepted and appreciated their devotion to her. She finds the city is now more comfortable for her since a modern Samurai like Flynn appeared before her. Wishing to give him lessons, she asks if he wants to spar. Agreeing to spar will start a battle. After the battle, she will be impressed by his skill and decides to return to the home of Lord Surya, her master. She tells him all he has to do is call her if he wants her aid before leaving. She will be unlocked for fusing after completing the quest.
"A sun goddess of Buddhism, her name means "light" or "heat haze." In Japan, she was worshipped by warriors, said to give the benefits of protection from harm and the ability to attack the enemy without being noticed. She is often portrayed as having 3 heads and 6 or 8 arms with weapons likes swords, bows, and vajra."
—Shin Megami Tensei IV Apocalypse compendium
Marishiten guards the temples that contain the jars of Aether which maintain the Tokugawa Mandala for the Divine Powers along with the Four Heavenly Kings. She can be found in the Okuji Temple, guarding the jar of Aether which contains the essence of Pride. Defeating Marishiten will unlock her for fusion in the Cathedral of Shadows.
Marishiten can teach Nanashi the Berserker God, Myriad Arrows, Makarakarn and Megidolaon skills through her Demon Whisper. She benefits from learning Gun, Physical, Ice, Almighty and support skills.
"Known as Marishiten in Japan, she is a sun goddess of Buddhism. Her name means "light" or "heat haze". In Japan, she was worshiped by warriors, said to give the benefits of protection from harm and the ability to attack the enemy without being noticed. She is often portrayed as having 3 heads, 6 or 8 arms with weapons like swords, bows, and vajra."