Sweet Rein
Sweet Rein is a shōjo manga by Sakura Tsukuba. A romantic comedy that is centered around the concept of Santa and Reindeers.
Plot
Kurumi Sagara is a high school student who one day bumps into Kaito, a young man who turn out to be a Reindeer. She learns that she has become a Santa, being able to command Kaito who regards her as his 'Master'. Now with her new duty as Santa, she is tasked with Kaito to deliver presents to children on Christmas.As a Reindeer is often attached to their Santa at first sight, Kaito also quickly develops feelings towards Kurumi, which Kurumi is not accustomed to. Kaito is determined to prove that his feelings are real and not just as a result of their unique relationship.
Setting
Santas are ordinary humans who are given the task to deliver presents to children the night before Christmas. They become Santas after physically coming in contact with their destined Reindeers. Once they become acquainted with their Reindeers, a rein connecting the Santa to the Reindeer appears, which only Santas and Reindeers can see. The rein is elastic and is invisible to normal people. It cannot be cut by physical objects. Whoever holds the reins of the reindeer controls them. One end of the reins are tied around the Santa's left hand, and the other end is implied to be connected to the reindeer's heart. Santas are also stated to be rarely female.Reindeers are people whose purpose are to help Santas deliver presents to children on Christmas. They tend to bond quickly to their Santas, usually exhibiting a master-servant relationship. Their bodies respond to any command their Santa gives, being able to fly and be summoned at any time to their master, regardless of their will. They are even able to come back after death to complete the master's order. The Reindeer's body may also react upon any indirect commands from their Santa. They are also able to transform into actual reindeers, which is the form they undertake when they are with their Santas delivering presents. The only time when the Reindeer can be exempt from their master's commands is when they kiss on the mouth, at this time, the reins will disappear. The reins will reappear when the Santa and Reindeer touch each other. Reindeers also share the physiological traits of actual reindeers, as shown that they are weak to the heat. They also experience heat during spring, in which Reindeers will begin attracting other humans of the opposite sex who lay their eyes on them. During this time, the reins of the Reindeer will turn red. Reindeers often appear as normal humans, a common feature are their vertical slit pupils. They also have the ability to fly in any form.
Black Santas are people who are sent to judge a Santa and Reindeer pair. They can do this by severing the rein of the pair and separating the reindeer and the Santa for a day. During this time, the Black Santa is in control of the Reindeer and can restrain them from their master. If the rein doesn't re-attach in the following day, then the Santa has to resign from their duty. There are also alternate ways for a Santa and Reindeer pair to be tested.
Black Reindeers are former Reindeers who have upset their Santas by their own free will, and are punished by being unable to die. Their Santas also have to resign. They are seen to be paired with a Black Santa.
Stray Reindeers are Black Reindeers who refuse to deliver presents or evaluate Santas. Because of this, they're punished by being forced to wander without purpose, if they receive a fatal wound, it will be healed quickly. Most Stray Reindeers are a result of their Santa's dying whilst the leash is still attached. Their leashes aren't connected to anything. They are unable to fly by themselves, however if any other Santa grabs onto their leash and commands them to fly, they will be able to. It's observed that a Reindeer's hair turns black when they become a Black Reindeer.