In the distant isle of Tenguu Island, there exists a society governed by a hierarchical color caste system. The Red, Yellow, and Blue colors are known as the "Primary Colors" and are the ruling class of the hierarchy. Below them are the "secondary colors": Purple, Green, and Orange. Those whose colors lie outside of the spectrum like Black however, are considered to be at the lowest rung of the caste and are automatically exiled underground to Yomi, where they are to never see the light of day again.
As the last and only surviving member of the enigmatic White clan on Tennyo Island, our heroine, Olympia (true name: Byakuya, though you can change this in the game proper), is tasked to perform a special ritual that brings light back to a world covered in darkness after a certain tragic event years ago. Having now turned 18, Olympia is on a quest to find her true love so she can continue her lineage in the hopes of restoring her fallen clan.
The visual novel contains the following tropes:
- All the Other Reindeer: Since she was taken from Tennyo Island at the age of 5, Olympia has been isolated from others her whole life. As the women of Tennyo Island are an enigma to the people of Tenguu Island thanks to their isolationist culture and mysticism brought about by their connection to the goddess Amaterasu, people either revere or fear Olympia, with no in-between, much to her dismay. This does, however, slowly change by the time Olympia sets foot on her own by her 18th birthday.
- Always Identical Twins: Averted with Kaina and Kanan, who have very distinct features as fraternal twin brothers. In fact, Kaina's hair is noticeably more yellow in color than Kanan's orange hair, resulting in them belonging to different classes.
- Ambition Is Evil: In Akaza's route, Olympia learns that there are rumors that Douma killed the previous leader of the Yellow in order to gain power. The rumors are half-right: He did poison the previous leader, but for far more personal reasons.
- Colourful Theme Naming: Keeping in line with the color themes of the story, most of the characters are named after the color of their respective clan. For example, Olympia's real name "Byakuya", means "white night" in Japanese, reflecting her heritage as a member of Tennyo Island's White clan, while Akaza's name can be read as "red sand", which is fitting for someone who belongs to the Red clan.
- Cool Old Guy: A recurring minor character is Fusou, the former leader of the Fuchsia. Fusou was once married to a woman of the White, and managed to retain some of his memories of his time on Tennyo Island. He often takes on a grandfatherly role toward Olympia. Tsukuyomi's Memoir reveals that Fusou is the father of Olympia's mother Hakua, meaning that he really is her grandfather.
- Eunuchs Are Evil: Kanan, who lost his penis at 15 after contracting haku, is a recurring villain.
- Fantastic Racism: The color class hierarchy in Tenguu Island guarantees and perpetuates discrimination against "lower class" colors like the Black. It's so bad that if someone belonging to a primary or secondary color were to have illicit relationships with those of the lower colors, they would automatically be exiled to Yomi without exception while their partner from the lower colors would be executed should they be caught - and a lot of times even being a member of one of the higher classes isn’t enough to save you from execution. The one exception to this rule is Olympia, as thanks to her special position, she's free to choose any partner regardless of their color, though many still try to dissuade her from going after the lower colors.
- Kuroba belongs to the Black clan, but wears a yellow shirt and has yellow eyes. This is because he was originally from the Yellow clan.
- There are a number of hints that Olympia's maid, Chigaya, is a woman of White before this is revealed in Akaza's route.
- In one of Yosuga's bad endings, Chigaya tells Olympia that she will accompany her to Tennyo Island.
- In Himuka's route, Chigaya says that her late husband was of the Red - one of the three Primary Classes, but Olympia notes that Chigaya's own hair seems to be a simple brown, suggesting that she belongs to a class that would normally not be allowed to marry someone from the Primary Classes. A woman of the White, on the other hand, can marry a man belonging to any color class.
- Finally, early on in Akaza's route, Chigaya offers to teach Olympia (who never got to learn the weaving that the women of White specialize in) how to weave, noting that she's pretty good at it herself.
- Historical Domain Character: One of Olympia's possible love interests is Amakusa Shirou Tokisada, who is noted to be an Outsider who came from Japan. Jigen reveals in his Memoir that his true identity is that of Nankoubou Tenkai. Douma doesn't explicitly reveal his name, but implies that he was Ashiya Douman.
- Last of Her Kind: Olympia is the last of the female-only White clan from Tennyo Island after all of them sans Olympia killed themselves when foolish men decided to somehow step foot on the island despite Amaterasu's protection. Akaza’s route reveals that her maid, Chigaya, is also a woman of White, albeit one who left Tennyo Island of her own accord before the Red Calamity. Yosuga is also the last of his clan, the Purple, as revealed in his route.
- Luke, I Am Your Father: Near the end of Akaza’s route, Lord Douma reveals to Olympia that he is her father, having fallen in love with her mother after washing up on Tennyo Island.
- One-Gender Race: It's noted that the women of the White only ever gave birth to daughters of the White, hence why they were allowed to marry men from any class. Akaza’s route reveals that he was born to a woman of White, but was not allowed to live on Tennyo Island due to having Red attributes.
- Rape by Proxy:
- In one of Tokisada's Bad Ends, Kanan drugs Olympia and his own brother, Kaina into thinking that the other is their lover and setting them upon each other.
- More disturbingly, one of Himuka's bad endings also has this happen, facilitated by Kanan and Sakyo, but perpetuated by Hairi, whose age is never given but is at least a few years younger than Olympia, who doesn't seem comfortable with it.
- Royal Inbreeding: In order to produce children that are capable of using Batsu, the Blue Clan frequently did this in the past. They’ve only started to move away from it and start having children with others because of frequent stillbirths and the general unhealthiness of their members.
- Shipping Torpedo: In most routes, Tsukuyomi is supportive of Olympia's choice in husband, but in Akaza's route, he discourages her relationship with him due to him suspecting that Akaza is the reincarnation of Susano'o, who was responsible for the death of Amaterasu. As the route progresses, he starts to interfere more. In one of Akaza's bad endings, he even lets the world end and takes Olympia with him to another one.
- Someone to Remember Him By: One of Yosuga's bad endings has Olympia realize that she's pregnant with his child and start to make plans to relocate back to Tennyo Island with the Shou created from Yosuga to raise the child.
- Suicide Is Shameful: When someone from the Primary or Secondary Colors dies, their deaths are handled by the Blue... unless they committed suicide, at which point the undertaker is called. It's said that not only will those who commit suicide not be allowed into Heaven, but those nearby will be cursed.
- Tsundere: Because of the way Akaza worded his suggestion that he marry Olympia if she's unable to find a husband within a year, Olympia spends the early part of his route denying her growing attraction to him. Towards the end of his route and in his bonus episode, Akaza notes that she takes after her father, Douma, in that respect.