Dimensional Chat Group with a System.

Looking around at his surrounding and seeing some weird people with Naruto headbands jumping on the roof-to-roof while spitting fire from their face, Kosuke is not-so-calm anymore. As a "Legal" Transmigrator and almost a Reincarnator, He is a person who has seen virtually everything. But finding that he is in a world filled with ninjas and shit, maybe his previous life experience is not-so-good anymore. "Sasuke Uchiha was the most powerful Shinobi to ever exist." His teacher once told him in the history class. He asked, "What about Naruto Uzumaki?" To which he got a reply, "Who? There is no such person in history." "Then what about Tailed-beasts and Otsutsuki's?" He asked with a hopeful gaze. "You mean Devil creature? Also, what Otsutsuki? Are you acting senile?" Since then, he realized that this world is Fucked up. …. But, a day before his Chunin exams, he got a mysterious Sign-in System. Which enabled him to get various rewards after sign-in at historical locations. Suddenly, a new type of voice rang in his mind… [You have been invited to Dimensional Chat Group] [Would you like to join?] Now, his sign-in scope is upgraded from a single world to a whole multiverse. Group members: Tony Stark, Sherlock Holmes, Saiki Kusuo, Nakiri Erina, Diana Prince, …