Polyleaders

Polyleaders is the poly ship between Ichika Hoshino, Minori Hanasato, Kohane Azusawa, Tsukasa Tenma and Kanade Yoisaki from the Project SEKAI fandom.

Canon
Ichika, Minori, Kohane, Tsukasa and Kanade are all in different units, but they are all the leaders of their units; Leo/need, MORE MORE JUMP!, Vivid BAD SQUAD, Wonderlands x Showtime and 25-ji Nightcord de. All of them are also girls, with the exception of Tsukasa. Ichika, Minori and Kohane attend Miyamasuzaka Girls' Academy while Tsukasa attends Kamiyama High School and Kanade takes online classes. Ichika, Minori and Kohane are first years while Tsukasa and Kande are second years.

Minori and Kohane are the only classmates within the group, and they are also best friends. Ichika is childhood friends with Tsukasa since he is the older brother of Ichika's childhood best friend. Ichika also became friends with Minori and Kohane when she sang with them in the "Singing Among the Cherry Blossoms" event. Ichika became friends with Kanade at the music store.

The five of them have plenty of official art together, along with Hatsune Miku, due to them being leaders of their respective groups.

Scramble Fan Festival!
Ichika, Minori and Kohane talk about their worries as they eat lunch on the school rooftop together. This helps them feel less alone, and they work through things together. The trio also decides to go to a VIRTUAL SINGER Fan Festival together. The three bring Nene to the Fan Festival, and she gets the rest of her troupe to help prepare for the festival. Kanade hears about the festival online and decides to attend as well.

During the festival, Tsukasa cheers up Minori and gives her courage to go on stage.

Where Feelings Come Together
When Ichika is walking down scramble crossing, she vaguely hears Miku's voice, which is being streamed downtown to promote the annual Virtual Singer Fan Festival. Upon hearing, she also remembers the Miku from her SEKAI.

After shopping, Minori and Kohane also hear the Fan Festival trailer. Both of them remember Miku from their SEKAI as well and imply it to each other without making it blatantly obvious about their SEKAI which is supposedly meant to be kept secret to others who don't already know about it. After visiting her father, Kanade also hears it in around the same area, and also remember's Miku from her SEKAI. She decides to visit her later.

Tsukasa visits SEKAI to meet Miku for practice, as she is not there immediately, Tsukasa reminisces and remembers his and Miku's first meeting. He then notices a glowing ball of light which also seemed to affect the phones of the other group leaders.

The five arrive in a SEKAI fragment shortly after, and upon hearing each other's voices, they rush forward in an attempt to find the source and all of them end up near a large tree.

According to Miku, the place they were at was a fragment SEKAI, and it has formed due to intertwined feelings between the five. On the tree in the SEKAI, there were sheets of paper which were all relevant to each of their respective units. Miku clarifies this is a "Wishing Tree", which is made up of their hopes and dreams.

All of them thank Miku for guiding them along their journey towards their dreams. But before Ichika does, the SEKAI fragment fades, and the five, after returning to where they were before visiting the SEKAI fragment, unfortunately remember almost nothing about it.

Fanon
Polyleaders is a rarepair, but there are some people that do ship it. Since there aren't a lot of interactions between the group, people tend to ship each of the characters with characters in their unit instead. Polyleaders is mostly rivaled by Ichisaki, Minoharu, Anhane, RuiKasa and Kanamafu, though there are many other rivals. Polyleaders is mostly seen as a friendship rather than a romantic ship.

Fandom
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Trivia

 * So far, Polyleaders have sung two songs together (Gunjou Sanka and Journey, both which are the anniversary songs for Project SEKAI).