Tsukuyomi

Tsukuyomi (ツクヨミ, Tsukuyomi) is a psychic research organization that experimented on Tatsumaki when she was a little girl.

Overview
Tsukuyomi has been researching psychic power and claimed that it is for the advancement of humanity. Members of this organization consist of scientists who have done many experiments on Tatsumaki. They have at least one research facility. They appear to have been producing artificial espers.

History
Many years ago, when Tatsumaki was only seven years old, this organization discovered her psychic power and took her away from her adoptive parents after giving them money in exchange. They did notice a two-year-old Fubuki as well, but decided to let her be because unlike Tatsumaki, she had not developed her psychic power yet.

For three years, Tatsumaki lived in a research facility of Tsukuyomi and was experimented by them until a hybrid monster broke free from its containment and went on a rampage. Tatsumaki was locked in a cell and was pretending that she could not use her powers. People in the facility abandoned her and ran for their lives. The hybrid monster eventually came to her holding cell and smashed down the door. It was soon killed by Blast who came and saved Tatsumaki. Once free, Tatsumaki went off to go to Fubuki, with Tsukuyomi becoming aware of this and trying to retrieve her. After meeting Fubuki, Tatsumaki was ambushed by four Tsukuyomi agents who presumably got killed by her soon afterward. A child Fubuki witnessed this and became scared of her older sister.

Psychic Sisters Arc
After the Monster Association is defeated, the Tsukuyomi learn that the Hero Association had captured Psykos. The Tsukuyomi offer a large sum of money to the Hero Association in exchange for Psykos, and being low on both funds and morality, they accept. The Tsukuyomi then send an agent called Apollo to collect Psykos. When Apollo arrives, he is escorted to her cell where he refers to Psykos as a "sample" that would bring a great leap in research progress for them. It is also revealed that the Tsukuyomi somehow knew about Psykos's "third eye" ability to see into the future and would research it with a thorough craniotomy.

Tatsumaki and Fubuki were aware of the Tsukuyomi and intercept Apollo. He is greatly outmatched by Tatsumaki, but manages to turn the tables and almost capture the two of them and Psykos for research. His attempt to capture them fails, but he manages to escape along with another unnamed Tsukuyomi agent who was undercover in the Fubuki Group.

Trivia

 * Psykos is shown to be linked somehow with this organization when she responds violently to the mention of the name Tsukuyomi.