Dazai is not based on a true story. Usually, characters like Dazai are formed through the author's imagination and artistic expression to create an engaging narrative for the readers.
Osamu Dazai's Collection was a collection of novels by the Japanese novelist Osamu Dazai. It included many works covering different styles such as novels, essays, and essays. The collection's theme was to describe the dark side of human nature. The style was humorous and satirical, and it was deeply loved by readers. Among them, the most famous works included "The World's Disqualification","The Setting Sun","The Wife of Wei Yong" and so on.
First, study the minor character from the movie. Notice their traits, actions, and any hints of their backstory. For example, if it's a random Resistance pilot, you could give them a fear of heights which they have to overcome. Start with their current state in the movie and then gradually change them. Maybe they have a life - changing encounter during the events of The Last Jedi, like saving a major character. This could boost their confidence and change their perspective on the war and their role in it.