There are always more places I'd like to visit, and many I'd like to revisit in different seasons.
My top wish is to someday be able to visit Korakuen Garden in Okayama in the snow. I also want to see the grass-burning festival there. I've seen the garden with plum blossoms, cherry blossoms, azaleas, irises, waterlilies, autumn leaves, and a few of the other events. Snow is so rare there, especially snow that sticks. There are a lot of places I'd like to see with snow, actually.
-Hokkaido: I went to Hokkaido for the first time this winter. I'd like to go back to see the flowers blooming in Furano/Biei, visit some of the national parks, Matsumae Castle and Goryokaku's cherry blossoms, and what is considered to be the most difficult to reach of the "Top 100 Castles", the Nemuro Peninsula's Chashi sites.
-Tohoku: I love Yamagata Prefecture, so it'd be nice to go back. I want to see the Tanabata Festival in Sendai (it's already been cancelled for 2020). I want to visit the kokeshi onsen that I haven't visited throughout the region. Exploring the coastal area of Akita and Nyuto Onsen. I've not yet been to Aomori or Iwate, so Mount Osore, Hirosaki Castle, Ryusendo Cave, Hiraizumi, etc.
-Kanto: I'd like to see the marshlands in Nikko and Nikko in the autumn. The frozen waterfall light-ups in Chichibu, the Chichibu Pilgrimage, nemophila at Hitachi Seaside Park, maybe Kairakuen outside of the plum season, a bit more of Chiba, Hachioji Castle, Kamakura with hydrangeas, Oshi Castle, and maybe Hakone.
-Chubu: More castles in Nagano, Okuhida Onsen and the ropeway, the Noto Peninsula, Kurobe Gorge and the snow corridor, the Yatsuo's Bon Odori, Naegi Castle, northern Niigata, Sado Island, Takada Castle's cherry blossom festival and light-up, the cherry blossoms at Ichijodani.
Kansai: Kumano Hongu Taisha, Shingu Castle, coastal areas in Wakayama, Akagi Castle
Chugoku: Kagamino (onsen, gorge, waterfall), stay overnight at Yubara Onsen, Shinjo Town's cherry blossom road, Niimi's caves and waterfall, the Katatetsu Cycling Road to Chausayama Castle, Chizu, the gorge and natural bridge in northeastern Hiroshima Prefecture, climb to the top of Mount Daisen, cherry blossoms at Kintai-kyo Bridge, Oki Islands
Shikoku: Kawanoe Castle, return to Iya Valley, Ritsurin Garden's light-up, Kawashima Castle, Ashizuri Cape, Shikoku Karst, the gorge on Shodoshima Island, Niyodo River, whale watching in Kochi, Ioki area
Kyushu: Lots more castles, Yakushima, Oita/Kumamoto (haven't been to either)...