After the events of of part 3 Kaori went on to finish high school and peruse a bachelors degree in the preforming arts. She attended the same college as Jotaro, sacrificing her quality of education so stay with her only friend. It took a while, but a year after graduating college she finally scored a big acting gig, and her career finally took off. 

By the time DIU rolls around she is married to Jotaro and the mother of 4-year-old Jolyne, who is staying with Kaori's mother when she heads to Morioh with her husband. Kaori is a bit of an absentee mother- often preoccupied with her job and leaving her mother and Jotaro to take care of the child. She grows to regret choosing her work over her child, but believes whats done is done and continues to do so until after what happens in Morioh.

Josuke's relationship with his father pushes Kaori to actually take time to think about her relationship with her daughter. She doesn't want to feel like a stranger to her daughter anymore. She speaks with Joseph very often while in Morioh, so his guilt slowly but surely seeps its way into her mind.

Kaori has a soft spot for the group of boys that helps with the investigation of Kira. The group almost reminds her of the friend group consisting of her, Jotaro, and Kakyoin in how they interact. It gives her a small bit of hope, and motivation so they can live happily, with out the worry of the same fate that had claimed Kakyoin.

While Kaori's stand doesn't really help too much with finding Kira, she still assists Jotaro claiming "It'll help her get into character for an upcoming role." Despite the terrible excuse to look at classified information, Jotaro allows her to do so and her investigative skills prove to be quite helpful.