He might face powerful ninja with unique abilities. These could be ninja who can manipulate elements in very dangerous ways, like creating huge firestorms or massive floods. Naruto would have to use the kyoketsu shoge knife cleverly to counter their attacks.
Perhaps he has to deal with some sort of shadow - based enemies. These enemies can disappear into shadows and reappear suddenly to attack. Naruto would use the kyoketsu shoge knife's chain to quickly lash out at the shadows and detect their presence, while also using the blade to defend himself when they materialize.
Maybe his godlike state gives him superhuman reflexes, allowing him to handle the kyoketsu shoge knife with extreme precision. He can anticipate his opponents' moves better and use the unique features of the knife, like the chain, more effectively in combat.
The plot could involve Naruto being in a super - powerful form (godlike) and using the kyoketsu shoge in unique ways. Maybe he uses it to fight against powerful new enemies that are immune to his regular jutsu. He could also use it to protect his village in a more stealthy and unexpected manner compared to his usual flashy attacks.
One antagonist could be a corrupted version of one of Naruto's old friends. Maybe they were influenced by some dark force and now have powers that rival Naruto's. They would oppose Naruto not only because of the power of the kyoketsu shoge but also due to their twisted view of the ninja world. Also, there could be a group of interdimensional invaders who see Naruto's power and the kyoketsu shoge as a threat to their plans of conquering the ninja world. They would use their advanced technology and unique abilities to try and defeat Naruto.
Well, perhaps in this fanfic, Naruto's use of the chained knife could be part of a new fighting style he develops. Maybe he discovers the chained knife during a mission in a mysterious land. He then has to train hard to master it. As he is godlike, he quickly adapts and uses it to defeat powerful enemies in unique ways, like combining his chakra with the chained knife's movements.
Maybe it was a gift from an old friend or a mentor. It could be a family heirloom that he just discovered, which has some special powers or significance related to his Uzumaki heritage.
Using the chained knife could add a new dimension to Naruto's character. It could show his adaptability. He is already powerful as a godlike being, but with the chained knife, he has to learn new combat strategies. This shows that he is always looking for ways to improve and protect his village. He might become more stealthy in combat, using the chained knife for surprise attacks.
Well, it might make his attacks more direct and lethal. With a knife, Naruto could add a new dimension to his close - combat moves. He could use it for quick slashes and stabs, which is different from his usual jutsu - based attacks.
One possible technique could be the 'Chakra - Infused Slice'. The knife master would channel their chakra into the blade, making it able to cut through even the toughest defenses like it was butter. This would require precise chakra control, which is a common theme in Naruto.
It could cause some of his friends to be worried about him. They might be afraid that the power of the demon knife will change Naruto for the worse. For example, Sasuke might be especially suspicious, which could strain their relationship further.
Kakashi is another one. With his sharingan and his experience as a ninja, he could be involved in a fanfic where he uncovers a conspiracy related to a set of cursed knives. He then has to use his wits and combat skills to deal with the situation before the knives fall into the wrong hands.