rengoku power level

No, Rengoku is not alive in the manga. He tragically died during a battle.

Yes, Rengoku did die in the manga.

Yes, Rengoku does die in the manga.

Rengoku doesn't turn into a demon in the manga. His character arc stays true to his heroic nature and doesn't involve any demonic changes.

They have some connections but not overly direct. Their storylines might intersect at certain points but not in a major way.

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.

Rengoku remains deceased in the manga. His character's fate is set, and there's no resurrection. It adds depth and gravity to the narrative.

Fan Xian's strength was around the eighth rank. Although he had won the battle with Cheng Jushu easily, he had not surpassed the level of the Eighth Stage. In the battle before Fan Xian and Teng Zijing joined forces to deal with Cheng Jushu, his strength had increased. He also said that after that battle, his zhenqi had gone up another level. Fan Xian's hearing had not reached the level of the ninth-level ace Yan Xiaoyi, so he could deduce that his strength should be between the eighth and ninth-level. However, the specific level of the expert was not explicitly mentioned.