Attention this recommendation might contain spoilers.
- A tragic past event.
- Blue haired hero was raised as a girl wearing long hair and yukata.
- Hero possesses inside him a great power in the form of a sword (Stone Sword/Blade of life).
- TG is more romance and Hakkenden is more "friendship".
- Beautiful animation & supernatural events/beings.
Both have Great art, fantasy, comedy and drama. Both involve gods, a possessed girl/woman, a present that is affected by events of the past in a place where everyone is connected somehow, incest, a "punishment"/curse, Love, random events and a hugely confusing plot.
Both anime's are focused around spirits, magic and the old japan. and both have the side elements of humor, ecchi and romance. they both have the same atmosphere. and where both drawn bij amazing artists.
Both series have a surreal fantasy element that leaves you wondering what is actually happening even though they both are set in a modern school setting. Theres a character driving a car recklessly all around campus in both series. There are characters that are 'characters' in all sense of the word; they are simplistic and comedic in their focus. There is even plenty of shoujo-ai for everyone in both.
both series are focused on the old japan, mengeld with the modern life of a high school student. Old traditions come forward and in both series there's a lot of traditional japanese clothing. Both have elements like mysterie and death, though Touka gettan also has comedy elements and is a bit more cheerfull and ecchi.