I'm not familiar with the author of this novel. It could be an indie author or someone relatively new in the literary world. Maybe it's a self - published work, which would make it even more difficult to know the author without some research.
The 'Woman in the White Kimono' could potentially be a character - centered novel. The white kimono might be a symbol. Maybe it's a love story where the white kimono has some significance in the relationship, like it was a gift or something she wore on a special occasion that led to certain events in the story. Or it could be about a woman's journey in a particular culture where the white kimono is a traditional garment, and her experiences are explored through that cultural lens.
One idea could be that Naruto wears a kimono for a special diplomatic event in the Hidden Leaf. It could be a traditional kimono passed down in his family, and while wearing it, he has to learn the proper etiquette associated with it, which leads to some humorous situations as he's not used to such formality.
Nezuko is initially 12 years old in the manga. As the story unfolds, her age doesn't change significantly in a traditional sense, but her character development is quite remarkable.