Yuri Unite is a fantasy yuri visual novel about three princesses from different kingdoms, each with their own plans to win the war. Not knowing one of them has other ways to win the war by winning their hearts instead.

Princess Helene wants to end the 200 years old war between the Three Kingdoms. Her father wants to use her skill 'Bookworm' which allows her to read any kind of book in this world with the access of limitless knowledge her kingdom is on to defeat the other kingdoms.

Princess Helene is sent to Saint Lilium Girls School, a school located on an island blessed by the goddess where war is out of reach. Princess Helene was supposed to be sent there to read the books even the great wizards can't read, but unbeknownst to everyone she has other plans on her own to win the princesses hearts before anyone else, and unbeknownst to her the princesses are not as sheltered as she might think.

[From Itch.io]