Here are some great films that are available subtitled and that would be excellent context before heading to Japan:
Dragnet Girl (Ozu Yasujirō, 1933)
Mr. Thank You (Shimizu Hiroshi, 1936)
Humanity and Paper Balloons (Yamanaka Sadao, 1937)
Drunken Angel (Kurosawa Akira, 1948)
Ugetsu (Mizoguchi Kenji, 1953)
When a Woman Ascends the Stairs (Naruse Mikio, 1960)
Pigs and Battleships (Imamura Shōhei, 1961)
Death by Hanging (Ōshima Nagisa, 1968)
Funeral Parade of Roses (Matsumoto Toshio, 1969)
The Shiranui Sea (Tsuchimoto Noriaki, 1975)
Family Game (Morita Yoshimitsu, 1983)
Nausicaä of the Valley of Wind (Miyazaki Hayao, 1984)
The Funeral (Itami Jūzō, 1984)
The Emperor's Naked Army Marches On (Hara Kazuo, 1987)
Only Yesterday (Takahata Isao, 1991)
Maboroshi (Koreeda Hirokazu, 1995)
Perfect Blue (Kon Satoshi, 1997)
Eureka (Aoyama Shinji, 2000)
Hush! (Hashiguchi Ryōsuke, 2001)
All About Lily Chou-Chou (Iwai Shunji, 2001)
Go (Yukisada Isao, 2001)
Sway (Nishikawa Miwa, 2006)
Tokyo Sonata (Kurosawa Kiyoshi, 2008)
Instant Swamp (Miki Satoshi, 2009)
Nuclear Nation (Funahashi Atsushi, 2012)
Come and Go (Kah Wai Lim, 2020)
Ushiku (Ian Thomas Ash, 2021)