Yes, there might be. Fanfiction websites are filled with all kinds of creative and unique crossovers. You can start by checking popular fanfiction platforms like FanFiction.net or Archive of Our Own. Just search for 'naruto is the soul king' and see what comes up.
Crooked Soul was a character in the novel "Mortal Cultivation Legend" and its derivative works. He was a disciple of Yellow Maple Valley and a mid Foundation Establishment cultivator. He was later devoured by Han Li and became his second Nascent Soul. Wang Taibao was a character in the novel " My Senior Brother Is Too Stable " and its derivative works. He was Li Changshou's senior brother and the second son of the Nine-Tailed Demon Fox Clan. His realm was at the mid-stage Body Integration Stage.
While waiting for the TV series, he could also click on the link below to read the classic original work of " The Legend of Mortal Cultivation "!
Another interesting concept is a fusion of Ichigo's Soul Reaper powers with the weapon - meister system in Soul Eater. Ichigo could form a bond with one of the Soul Eater weapons, like Soul Evans. Their combined powers would create a new and powerful form of combat that has never been seen before in either world.
Another theme is the exploration of the Soul Society's hierarchy. As a male soul reaper, Ichigo has to navigate through the complex social and power structures in the Soul Society. This can lead to conflicts, as he might question some of the old traditions or face opposition from those in higher positions. These themes combined make the 'ichigo only male soul reaper fanfiction' quite engaging and full of drama.
Fem Ichigo would likely be a very influential figure in Soul Society. As Byakuya's mother, she would be part of the Kuchiki family. She could be involved in the family's decision - making processes, perhaps having a say in matters regarding family honor, alliances, and the training of the younger members. Her unique abilities, which we assume she has from being an Ichigo - like character, could also be used to protect Soul Society from threats. For example, if there are Hollows attacking, she could use her sword skills to fight them off.
In these fanfictions, Ichigo often starts as a more naive character in the past. But as he experiences events again with his new knowledge as the King of Hollows, he becomes more confident. For example, when facing early enemies, he uses his Hollow powers more effectively. His understanding of the complex relationships between different spiritual beings also deepens. He realizes that not all Hollows are simply evil and that there are more shades of gray in the world of Soul Reapers, Quincies, and Hollows.
One great 'ichigo only male soul reaper fanfiction' could be 'Ichigo's Ascent'. It focuses on Ichigo's journey as a male soul reaper, exploring his growth in power and his relationships with other male soul reapers in a really engaging way.
The Silver Moon Wolf King martial soul originated from the Chinese web novel author, Tang Family's Third Young Master (Zhang Wei), who wrote a series of long fantasy novels,"Douluo Continent" and its derivative works.
In the novel, the Silver Moon Wolf King spirit was a power attack type beast spirit, and its owner was the Star Luo Empire's White Tiger Duke's Di son Dai Mubai. This spirit can use first spirit ability White Tiger Barrier, second spirit ability White Tiger Light Wave, third spirit ability White Tiger Vajra Transformation, fourth spirit ability White Tiger Meteor Shower, fifth spirit ability White Tiger Demon God Transformation, sixth spirit ability White Tiger Destruction Kill, seventh spirit ability White Tiger Avatar, eighth spirit ability unknown, ninth spirit ability unknown.
While waiting for the TV series, he could also click on the link below to read the classic original work of "The Legend of Mortal Cultivation"!
Ichigo and Maka would be really interesting. Maka is all about order and the pursuit of making her weapon, Soul, into a Death Scythe. Ichigo, on the other hand, has his own code as a Soul Reaper. They could clash over their different ways of dealing with souls and the afterlife, but also learn from each other.
One possible plot could be that Naruto is somehow transported to the world where the Soul King exists. He discovers his new role as the Soul King and has to learn the rules and powers associated with it. He might use his ninja training to face the threats that come to the Soul King's realm.