Four Heavenly Beasts

The Four Heavenly Beasts (四神) are a group of divine beasts which had been summoned and are currently contracted by Touya Mochizuki.

Overview
Divine Beasts (神獣) are a legendary type of summoned beasts and, as the name suggests, divine beings. By the nature of the summoning magic, anyone with dark attribute aptitude has a chance to summon one of the heavenly beasts. Fusing one's magic with one of the heavenly beast's magic and enchanting special summoning spell will allow the summoner to summon the other heavenly beasts directly. Certain requirement needs to be fulfilled prior to making contract with the summoned beast and because the heavenly beasts are high class summon, a higher stake of request is possible.

The first heavenly beast introduced is the White Tiger (白虎), the White Monarch (白帝). She was summoned when Touya Mochizuki was learning the summoning magic under the supervision of Yumina. Her request was to test the quantity and the quality of the magic of her summoner by pouring magic on to her. Unfortunately (or fortunately, depends on the point of view), Touya has an immense amount of mana and is also able to replenish said mana extremely fast, and the resulting pressure was able to easily knock the tiger unconscious. She received Kohaku (琥珀) as her name.

The second heavenly beast being summoned is the Genbu (玄武), the Black Monarch (玄帝). This unison of giant tortoise and black serpent beast was summoned by Touya Mochizuki after fusing his summoning spell with Kohaku's magic. They was summoned to help Touya enter one of the teleportation magic circles. Their request was to defeat them until the sun set. Using a combination of the 「Slip」 and 「Program」 spells, Touya sadistically made them roll continuously on themselves until the fight reached the time limit. After being ridiculously defeated, they are named Kokuyou (黒曜) & Sango (珊瑚) by Touya.

The third heavenly beast summoned is The Vermillion Bird, the Flame Monarch (炎帝). She was summoned by Touya Mochizuki after fusing his summoning spell with Kohaku's and Kokuyou and Sango's magic. Touya needed her minions, the bird beasts, to help him find another Babylonian ruin. After surprisingly seeing that Touya already had made contract with two of her colleagues, she calmly asked Touya about her name directly without making any request. She was then named Kougyoku (紅玉).

The last heavenly beast to be summoned is the The Azure Dragon (青竜), the Azure Monarch (蒼帝). She was summoned by Touya Mochizuki after fusing his summoning spell with Kohaku's, Kokuyou and Sango's, and Kougyoku's magic. She was called after several incident that involving dragons and wyverns. She was interested in Touya's ability that was able to take down all her heavenly friends. During the test fight, Touya used both and  to push the dragon's body down. After some difficulties to tried to get up, she realized her foolishness. Being able to cast a strong which require enormous amount of mana while also using this mana to manifest all the other heavenly beasts without losing any beat was not an ordinary task. After admitting her defeat, she was named Luli (瑠璃).

Abilities

 * Intimidation Aura: All heavenly beasts are able to release suppressing aura that renders all individuals which have lower magic level in respect to the heavenly beast immobile.
 * Long-Ranged Telepathic Communication: All heavenly beasts are able to make telepathic communication among themselves and with their master regardless the distance. They also able to include other people into their communication line.
 * Form Transformation: All heavenly beasts are able to change their menacing true form appearance into cute young beast form (Child Form) and back as they pleased.

Trivia

 * This group mostly based on the four Chinese constellation mythological creatures which consist of Azure Dragon of the East, Vermilion Bird of the South, White Tiger of the West, and Black Turtle of the North.
 * Kohaku, Kougyoku, and Luli's name are based after Gemstones while Kokuyou and Sango's names are based after earth's natural entities.
 * It is later revealed that most of them are female, leaving only Kokuyou as a male of the group.
 * Prior to the reveal, Touya Mochizuki had mistaken Kohaku as a male.
 * According to the character introduction #2, Kokuyou is a male but a female in heart.