I sat down to watch the 2017 sequel "Shinjuku Suwan II" (aka "Shinjuku Swan II") immediately after having sat through the 2015 "Shinjuku Suwan" movie. And I have to say that writers Mataichirô Yamamoto sort of delivered an okay script, though it was a little bit watered down in comparison to the 2015 movie.
Director Sion Sono returned to director this 2017 sequel, which was a nice thing, and some of the cast members from the first movie returned to reprise their roles as well.
The storyline in "Shinjuku Suwan II" felt a bit weak in comparison to the first movie, however I will say that this 2017 sequel would actually suffice well enough as a stand-alone movie if you haven't seen the 2015 movie. But the storyline in "Shinjuku Suwan II" felt a little bit rushed and not a thoroughly thought through as the original movie. Sure, there were good parts to the storyline as well.
The acting performances in the movie were good, and the character gallery in "Shinjuku Suwan II" was as good as in the 2015 "Shinjuku Suwan" movie, so that counted for something for sure.
My rating of "Shinjuku Suwan II" lands on a five out of ten stars.