He could transform the building into a ninja academy annex. Naruto loves teaching and passing on his knowledge. In this annex, he could offer advanced ninja training, focusing on things he has learned from his own experiences, like dealing with powerful enemies and using the power of friendship and determination.
He could turn it into a training ground for young wizards and witches. Teach them how to defend themselves against the dark arts, just like how he was taught at Hogwarts.
Perhaps it's a community building. Naruto is a very community - oriented person. He could own a building that serves as a place for the villagers to gather, like a community center. There could be a cafeteria, a place for kids to play, and rooms for meetings and celebrations.
In the fanfiction, he might own a building that is actually a magical library. Since Harry has always been interested in knowledge, this building could be full of rare and ancient magic books. It could also be a place where wizards and witches from all over come to study and research, and Harry, as the owner, would be in charge of protecting these precious knowledge resources.
One possible storyline could be Naruto renovating the apartment building to make it a better place for the villagers to live. He might use his ninja skills to do some unique construction work.
There could also be external threats. Maybe other villains or rival ninja clans see the apartment building as a target. They might try to take it over or destroy it to undermine Naruto's influence in the village. Naruto would then have to use his combat skills and strategic thinking to protect his property.
Sakura could be one of his partners. She is smart and has medical skills which could be useful in a business, for example, if it's a health - related business like a spa or a herbal medicine store.
His leadership skills could improve significantly. In this fanfiction scenario, if Naruto is in a position to 'own' his interactions with Kurenai, he would be leading in various aspects. This could mean better communication skills, being able to listen to Kurenai's thoughts and then making well - thought - out plans. He would grow into a more well - rounded leader, not just on the battlefield but also in relationships within the ninja community.
Without more context, it's hard to say exactly who 'he' is. It could be any fan of the Harry Potter series who has a particular interest in Hermione and has created or taken on some form of ownership in relation to fanfiction about her.
He might try to imitate Frieza's style. Naruto is known for his orange jumpsuit, but he could perhaps add some elements of Frieza's purple and white color scheme to his outfit. Also, he might start using more of an authoritarian tone like Frieza when dealing with his enemies.
Maybe he buys a training building so that he can practice his ninja skills without being disturbed. It could have special facilities for his shadow clone jutsu practice.