One idea could be that Mugetsu Ichigo finds himself in an alternate universe where he has to team up with his other - self from that universe to defeat a powerful new enemy. Maybe this enemy has the ability to nullify his Zanpakuto powers, forcing him to rely on new and creative combat strategies.
A possible plot could involve Mugetsu Ichigo being cursed by a powerful sorcerer. The curse slowly drains his spiritual energy, and he has to find a way to break it. In his journey to break the curse, he crosses paths with various characters who either help or hinder his progress. This could lead to some intense battles and character - development moments as he struggles to regain his full strength.
Maybe in the fanfic, Mugetsu Ichigo teams up with some unexpected characters from another series. For example, he could meet characters who have unique abilities that complement his own, and together they face a powerful common enemy that neither could defeat alone. This would lead to some interesting character interactions and power combinations.
One idea could be that Mugetsu Ichigo somehow ends up at the High School DxD school and has to deal with the different factions there. He might use his unique powers to solve some of the school's problems.
Well, perhaps in this fanfiction, Ichigo in Mugetsu form is stuck in a dimension where time and space work differently. He could start losing control of his Mugetsu powers and has to learn to master them again in this new environment. Along the way, he meets a character who has knowledge about his situation and helps him on his journey, which involves facing various challenges and foes.
One idea could be Ichigo getting transported to a different dimension where he meets various female characters from different anime. They all fall for his unique powers and his sense of justice. For example, he could meet a magical girl who is intrigued by his sword skills and a strong - willed ninja girl who admires his courage.
Maybe in a Fullbring Ichigo crossover fanfiction, Ichigo's Fullbring could somehow get mixed up with a magical artifact from another fictional realm. This causes him to gain new and unpredictable powers. He then has to journey through different dimensions to find a way to control these powers while also being chased by powerful enemies who want the artifact for themselves.
One idea could be Ichigo being transported to a different anime world where he meets a harem of characters from that world. For example, if he ended up in the Naruto world, he could encounter female ninja who are intrigued by his unique powers and personality. Another plot could involve a magical spell that accidentally creates a harem situation for Ichigo in his own Bleach world, with various female characters suddenly having strong feelings for him. Maybe there's a time - travel element where Ichigo goes back in time and gathers a harem of historical figures with spiritual powers.
One plot idea could be that Ichigo somehow gets transported to the FMA world. He might initially be confused by the alchemical rules but then use his Soul Reaper powers in unique ways. For example, his Zanpakuto could be seen as a form of alchemical weapon, and he could fight alongside the Elric brothers against the homunculi. Another idea is that the Philosopher's Stone has some connection to the Hollow within Ichigo, and characters from both universes have to work together to prevent a catastrophic event.
One idea could be that Ichigo discovers he has hidden Quincy powers that are much stronger than he thought. This could lead to him having to train with Quincy mentors to control it, while also dealing with his Soul Reaper duties.
A cool plot could be that there's a magical artifact that has the power to grant any wish. Ichigo and Erza both hear about it independently and end up chasing it. When they meet, they initially think the other is an enemy. But as they start to understand each other's motives, they decide to share the wish if they get the artifact. However, they face many challenges along the way, like traps set by other people who also want the artifact. Erza's strategic mind and Ichigo's determination would be great assets in this adventure.
A possible plot could be that Ichigo is transported to the Sekirei world during a battle with a powerful Hollow. There, he meets a Sekirei who has the ability to sense spiritual energy like he does. They form an alliance to stop a common enemy that is threatening both the Sekirei and the humans in that world. This enemy could be a rogue group of Sekirei who want to take over the world by any means necessary. Ichigo's unique powers and his experience in fighting powerful foes would be crucial in this scenario.