(Link for any updated/edited/future answers: https://docs.google.com/document/d/1X26GOgQ51TBVUJ8vsRBZi42QaFZ-mtxCAD2aD6Ax4kg/edit?usp=sharing)
The Hashimoto Clan temple lies within the outskirts of Shibuya, Japan, having been the home of the clan for many centuries now. It is a grand, traditional Japanese shrine surrounded by nature, isolated from the rest of the bustling city in order preserve its solitude, sanctity, and spirituality. Residing on its grounds are various family members, monks, and staff belonging to the Hashimoto's-- many of whom are currently practicing Onmyoji.
Hidden from the public and even most of the staff is a small layer existing beneath the temple-- accessed by a hidden, special elevator. This leads to a floor hosting the base of operations for the clan's more clandestine activities, which includes the sterile and cold laboratory where PROJECT: HYBRID-01 rests. Here, Rei lies in stasis within a small, specialized chamber until they are to be released for a mission.
The Hashimoto Clan is listed as having a few sources of revenue in official government records. The primary source is through the public-- namely through donations, sold talismans and amulets, and similar 'tourist' offerings. Much of the wealth that has been built over generations has also been invested by some of the higher-up members of the Clan so that it can continue to grow and expand.
However, the biggest source of money, as well as what the clan invests the most into, is its privately owned Onmyoji division. These Onmyoji will occasionally be granted permission to work for the public or government to keep up good will, but otherwise, they tend to operate and take on missions similarly to a group of mercenaries or PMC-- though this information is of course kept secret from the public.
Since their awakening, Rei Hashimoto has been trained and designed to be nothing but a weapon for the Hashimoto Clan. However, from the limited exposure and knowledge they've discovered about the world, a part of them has started developing a different ambition. Though they have yet to have the time to ponder this significantly, Rei wants to one day use their hybrid nature for the betterment of the world-- bridging the gap between traditional magic and new-age technology for the use of everyone. Currently, Rei remains steadfast, absolute, and unwavering in their loyalty towards the Hashimoto Clan, willing and designed to kill and die for whatever they desire. However, as they learn more and more about society, the part of their soul that wishes for something else has continued to grow stronger.
The vast majority of Rei's existence has taken place solely in stasis, lying motionless in their chamber as information and magic is fed to them. The few times they are allowed out of their chamber have mostly been for tests, simulations, and combat practice. However, one day, on the insistence of their Handler, Rei was allowed to roam completely outside the temple under their guidance-- granting them real life exposure to the world around them. Though this period was brief, it allowed Rei to realize what it was like to be free and in society. Since then, though trips to the outside world have been extraordinarily rare, the soul within Rei has started to develop ambitions of something more...
The Hashimoto Clan: A lineage of Onmyoji that has spanned for generations. The head of the clan is an old man named Satoshi Hashimoto, who is responsible for almost every executive decision made over the temple and family. In addition, he has two children-- Takeda Hashimoto, Satoshi's son who aids in many of the business and publicity side of things, and Katsumi Hashimoto-- who is an extremely prodigious and skilled Onmyoji.
The Doctor: The lead of the PROJECT: HYBRID-01 initiative, responsible for the development and creation of Rei. Extremely intelligent, controlling, and uncaring. A real mad scientist type, often seen in a well worn, robe-like lab coat. They primarily treat Rei as an experiment to be perfected, subjecting them to an extensive amount of testing, disassembly and reassembly.
The Handler, Takemi: The Onmyoji placed in charge of training and instructing Rei for outside missions. They are an older figure, somewhere around their 50's or 60's, possess a relaxed, composed, and worldly character, and insist on being referred to by their name-- Takemi. From their conversations, Rei has learned that they are likely a distant relative raised separately from the Hashimoto Clan, and have been an experienced Onmyoji for quite some time. Unlike everyone else in the clan, they seem to have decided to treat Rei like a person thus far.
Rei came into being just over six months ago, created in an underground, secret laboratory. They were made for the purposes of being a weapon by the Hashimoto Clan, a long-lasting clan of Onmyoji from Japan. The one responsible for leading their creation is only known as 'The Doctor' from Rei. They treat them as if they were a marvel of their own innovation-- a piece of technology that needed to be perfected, subjecting Rei to constant experimentation, disassembly, and testing. The rest of the clan treats Rei similarly, as an object or weapon to be commanded. The only exception is their Mission Hander, Takemi Hashimoto, who seems to hold some sympathy and acknowledgement of their sentience. Rei's training has mostly consisted of different calibration tests in the lab, and downloading/processing streams of information while they are in stasis. The only experiences they had of being in actual society before the Contract are the few times their Mission Handler has brought them outside.
Due to their circumstances, Rei has never been able to interact with many people, and thus, hasn't had the opportunity to form many bonds, relationships, or connections. The person closest to them is their Mission Handler, the only one to acknowledge their sentience, though their relationship is still primarily professional. However, the one thing that has stopped Rei from remaining an emotionless, calculating robot was the time when their Mission Handler brought them into the outside world. This brief moment allowed for Rei to understand what it was like to be free and among society, and see how people live their day to day lives. Since that moment, they have slowly started to conceive ambitions towards using their abilities to help others instead.