I recommend the book "Possibly a Fake Silver Soul". It tells the story of Jiang Cheng, a transmigrator, who met the owner of Xinghai District and his girlfriend, Jiang Hua, who were traveling in the universe in the dragon vein of a certain planet. Later, he came to Earth and met his teacher, Yoshida Shoyo, who had influenced his life. He also met a group of friends. This included the transmigrator Okita Soki. This is a Silver Soul Doujinshi novel, don't miss it. I hope you like this fairy's recommendation. Muah ~😗
One popular 'takasugi x katsura fanfic' is 'The Unlikely Bond'. It delves into their complex relationship, exploring how their different ideals and personalities interact. It has some really well - written dialogue that gives depth to their characters.
A theme of redemption can also be found. Maybe Takasugi has done something wrong and Katsura is there to help him find his way back. Or vice versa. Their relationship can be a vehicle for exploring how one can be redeemed through the love and support of a friend. And of course, adventure themes are common. They might go on some wild adventures together, facing enemies and solving mysteries along the way.
Gintama is purely fictional. It's filled with imaginative characters and scenarios that are not rooted in real-life events. The creators crafted a unique and entertaining fictional world for the audience.