Crossover challenge: Nasuverse x Death Note

Someone is reincarnated on Death Note with the Mystic Eyes of Death Perception, and know how to use them

This can be used to "kill" a death forced from the DN, that take form of strings, like the future in Kara no Kyōkai: Mirai Fukuin. Naturally it does not destroy the DN, but it saves the people whose string it cuts.

If you want it can also make the owner "see" shinigamis, but I suggest to not give the Owner the shinigamis eye-power too.

You can also decide to reincarnate someone that has already read Death Note. He/she can be on both sides or even a third party, but please do not make him/her as intelligent as L/light, but if he has DN manga knowledge he can relate to that knowledge

Stories that I intend to write/am writing:

1. Fate fragmented soul
   Fate/stay night / RWBY crossover;
   Shirou and Illya go escape to Remnant to hide from the clocktower, changing its future and discovering its past. [This is the story that occupies more of my time; I have already set Shirou, some major events, the allies and the enemies. I only need to write it]
2. Fate crimson blades
   Fate/stay night AU;
   What if...story Shirou's fate is changed when, two years after been adopted by Kiritsugu, a magus in japanese soil that should have been defeated from the counter force arrives too close to the Root, making Alaya summon a Counter Guardian to stop him. Guess who will be summoned? [The basic structure of the story is done, but I am conflicted to write it because of an event that will happen in the later chapters]This is the story of Shirou of Fate fragmented soul
3. Fate/ stay / fate Kaleid Crossover
   Reincarnation of Emiya Shirou on Fate Kaleid Illya's world.
   Emiya Shirou died while Hunting a Dead apostole ex disciple of the Wizard Marshall. Reincarnated on Fate/Kaleid he finally found out his true parents, but decide to leave them to save his father and his family from their destiny. But not everything goes as planned. [Unable to provide to details due to consultation with another author]
4. Fate/stay night / Gate;
   The wizard marshal asked Shirou Emiya, tohsaka Rin and Illya to help him understand what was happening in some universes that suddenly escaped the parallel line of worlds, this is because he do not know what would happen to him if he shift world so fast. The reward is that Shirou will have back his body.The 4 arrive to tokyo some months before the shift and Shirou and company find job in some pub. [This is a project, nothing is certain yet, Shirou is from a slighty different Universe from Heaven's feel probably, because Illya is too cute to die]
5. AU Issei in DC universe[Issei x Raven, it is a story I want to write only for the ship, but I know too few things on the DC universe to write it and it makes me cringe; Halfdragon!Issei Depressed!Issei]
6. Post-war ichigo to Rwby
   features an Ichigo from after Quincy war, the universe of Ichigo had a slighty shift from an action between the war with Aizen and the war with the quincy that due butterfly effect forced Kurosaki family to go to Remnant [another pearl that I wanted to write from some months; would like Ichigo/Rukia, Karin/Toshiro]
7. Ichigo fullbringer in One Piece
8. Ichigo to Fairy Tail

I am a university student that like reading and sometimes writing, but as I am expecially pedantic with the logic behind the story so I rarely do so.

I expecially do not like crossover stories that start with an MC trasported to another world without any reason, even transported to recharge the mana in the world I believe is better. Still, as usually the detail is completely ignored i tend to continue reading.