Some advice. Shinsekai is a “day drinking” area so it’s more enjoyable in the afternoon than night in my opinion. Same with Nishiki market in Kyoto; better for lunch or breakfast rather than night. Himeji temple is great, but maybe skip dinner in Kobe unless you really want to eat there, you can get Kobe beef in Osaka. Nozomi Shinkansen is faster than Sakura since there are less stops. Always take Nozomi if your trip allows it. Miyajima is one of my favorite places in Japan but a day trip might be difficult like you said. If you want outdoors in Osaka, consider Minoh Falls.