A crossover between Tensei Shitara Slime Datta Ken and Genjitsu no Yohane: SUNSHINE in the MIRROR. 

Suddenly, Rimuru's Tensura Team and Yohane's Maboroshi Yoha Team clash. How will they end up in this battle where the Tensura Team seems to have an overwhelming advantage...!?

One day, unremarkable college student Yuuhi Amamiya meets a talking lizard who asks for his help saving Earth from a crisis. Before he can refuse, Yuuhi is turned into a member of the Beast Knights and given a ring that gives him the psychic power “domain control.” He is then immediately attacked by an enemy! But just as all seems lost, he’s saved by the girl next door, Samidare. 
 
But it turns out Samidare isn’t really a savior of any kind… she’s actually a demon lord who wants to conquer Earth! Drawn to her absurd strength and evil charms, Yuuhi becomes her devoted servant and acts to support her wicked schemes. 
 
(Source: Crunchyroll)

Ever since coming across the world of boy’s rhythmic gymnastics during the last summer of junior-high, Shotaro Futaba has become fascinated with the sport. So when he enters Soshokuan Private High School, known as Ao High for short, he heads to the boy’s rhythmic gymnastics club, where he meets unique seniors and the ace of the team, Ryoya Misato. The members of the club each have their own passions, but they’ve put it all on the line with a single goal in mind. Now the next stage in their journey has arrived: the inter-high competition! 
(Source: Tokyo Otaku Mode)

STUDIO SIERRA