The 'Basara Novel' is a complex work. It often involves themes like adventure, power struggles, and character growth. It may tell the story of characters in a fictional world filled with political intrigue, battles, and relationships.
One idea could be a rengoku fanfic where he trains a new group of young slayers. It could focus on his unique teaching methods and how he instills his values in them.
Tanjiro would be a great character to pair with rengoku. Their different personalities could create an interesting interaction. Tanjiro's kind - hearted nature and rengoku's fiery determination could lead to some great storylines.