Regardless of my Issey fan + Jojo fan filter, I think this is a good movie. It is filled with strong Japanese-style beauty and horror. A lot of images and emotions lingered for a long time.
It is impressive that they used minimum CGI to create the maximum effect. The "reality" of the whole story increases tremendously because of it. I also like that while it's a horror story, every shot is visually beautiful. It actually intensifies the horridness.
The climax in the museum basement was seriously terrifying. I almost regretted seeing it since I have a low tolerance for that kind of thing. The way you suddenly realised you were staring at the painting after several seconds into the scene was perfect. And horrifying. The drowning effect and the fire were also effective. Until that point none of the hallucination content was shown, so those effects felt very real. That painting was so impactful just by itself. I still can't get that image out of my head... It literally radiated hatred.
I appreciated Izumi so much in the movie. She not only saved Emma from her illusion and guilt, but she also saved me from potential nightmares. Her positivity never wavered and had the ability to put Rohan's life ( and the story) back to normal. She made my heart warm up so easily and I love her.
Admittedly some explanation of the story might not be necessary. For example the content of each person's hallucination or the full back story of Yamamura the painter. It eliminates the audience's imagination and the beauty of mystery in the first half. It's a shame, but it's the choice they made. I think it didn't lessen the movie's value and it's nice to see new things coming from the short original manga.
Finally, I just want to shout out how good an actor Issey Takahashi is!!! He is the perfect Rohan, which isn't the news, but he never stopped to amaze me with his acting. There was just so much to read in his slightest facial muscle movement. I especially love what he did when his own hallucination emerged. He looked so uncharacteristically vulnerable. When Nanase appeared, there was a moment when he looked almost like 17, even similar to the actor who played young Rohan. Also, him playing Yamamura who turned crazier towards art was gorgeous.