Since there have been tons of reviews and impressions since the original post, I've provided direct links to all of them here - in chronological order (from oldest to newest) - for your convenience.

Goto Retreat Ray (by Nagasaki Joe)
Mt. Resort Unzen Kyushu Hotel (by Nagasaki Joe)
Modern Ryokan kishi-ke
Fufu Kyoto
Takachiho Ryokan Shinsen & Amane Resort Seikai (by zander86)
Bouyourou (2023 Jan.)
Miyajima Kinsuikan
Myoken Ishiharaso & Takefue (by jambalaya)
Amane Resort Gahama
Umioto Mari
Naoshima Ryokan Roka
Hoshino Resorts Kai Unzen (by Nagasaki Joe)
Fujiiso
Mifuneyama Rakuen Hotel (by Nagasaki Joe)
Iki Retreat Kairi Murakami
Tokachigawa Onsen Sanyoan
Akan Tsuruga Besso Hinanoza
Fufu Nikko (by Koen dc)
Wanosato (by Koen dc)
Fufu Kawaguchiko & Fufu Nikko (by Buster CT1K)
Ekoin Buddhist Temple / Ekoin breakfast (by RichardInSF)
Sanso Amanosato (by RichardInSF)
Zaborin (by cristmh)
Bouyourou & Takefue (by Fc912)
Nishimuraya Honkan (by Buster CT1K)
Gora Kadan (by TBD)
Bettei Senjuan
Kusatsu Onsen Kei
Kaichoro
Fuefukigawa Onsen Zabou
Kagaya Bettei Matsunomidori
Myoken Ishiharaso
Chalet Ivy Jozankei (by kyeung2)
Amane Resort Seikai & Kannawaen (by Michaeljinnyc)
Yoyokaku (by Michaeljinnyc)
Takimotokan Yukinosato (by buggy51)
Goto Retreat Ray
Takefue
Asaba, Myoken Ishiharaso & Takefue (by hl888)
Fufu Nikko (by nappingpanda)
Wanosato (by Michaeljinnyc)
Enowa Yufuin (by japanesegeek)
Takimotokan Yukinosato & Shogetsu (by Michaeljinnyc)
Sakurayu Sanshuyu & Atamiso (by Michaeljinnyc)
Takefue (by trainsupercommuter)
NEOLD Private House
Aizu Tsuruga Higashiyama Sohonzan
Shiki no Yado Michinokuan
Akan Tsuruga Besso Hinanoza (byMichaeljinnyc)
Wanosato (by peakshaving)
Sankara Hotel & Spa Yakushima (by mdlgto)
Kyo Yunohana Resort Suisen
Ryotei Hanzuiryo (by Nagasaki Joe)
Wanosato & Fufu Nikko (by pstm91)
Zaborin (by Fliar)
Takefue (by FlyingTurk1)
Ekoin, Sanso Amanosato & Taketoritei Maruyama (by Buster CT1K)
Gora Karaku (by stargold)
Asan Kotonami, Fufu Nikko, Fuefukigawa Onsen Zabou, Fufu Kawaguchiko, Asaba, Hakone Suishoen (by OWHKG2016)
Satoyama Jujo & Natsuse Onsen Miyakowasure (by NZJuniorDoc)
Asaba (by pdxerinsaarland)
Bettei Yaeno
Hanaichi
Kasenan Seni Onsen Iwanoyu
Satoyama Jujo - The House Izumi
Ryotei Hanzuiryo
Onyado Chikurintei
Enowa Yufuin
Sanso Tensui
Yado Shiontei
Yado Shiontei & Minamikan (by Fc912)
Shiguchi (by Fc912)
Hakone Gora Byakudan (by brownoarsman)
Asaba
Iki Retreat Kairi Murakami (by pWei)
ryugon & Satoyama Jujo (by sirky)
Lake Shikotsu Tsuruga Bessou Ao no Za (by pWei)
Sanso Amanosato, Sanso Tensui & Yufuin Rikka (by zander86)
Yama No Chaya (by LisainCA)
Tsuchiyu Bettei Satonoyu
Auberge Suzukane
Yamagata The Takinami
Fuji Seiran
Zaborin & Shiguchi (by mattjp)
Lake Shikotsu Tsuruga Besso Ao no Za
Chalet Ivy Jozankei
Shiguchi
Shiguchi (by nylonite)
Yamamizuki Bettei, Myoken Ishiharaso & Onyado Kawasemi by (by jpit2107)
Asaba & Arcana Izu (by Fc912)
Hanamurasaki (by LisainCA)
Kansuiro
Nara Kasuga Okuyama Tsukihitei
Fukudaya
Nakanobo Zuien
Iwanoyu and Yunohanaso (by zander86)
Kappo Ryokan Wakamatsu
Ryotei Kuki
Taiza Onsen Sumihei
Gekkoju Kurokawa (by Bristom)
Takachiho Ryokan Shinsen (by Bristom)
Takefue (by Bristom)
Myoken Ishiharaso (by Bristom)
Bettei Itsuki (by Bristom)
Fufu Nara (by Bristom)
Nishimuraya Honkan (by adlibitum)
Gora Kadan Fuji (by Fc912)
Yoshikawa small luxury inn Kyoto & Tempura (by adlibitum) (Photos: 1, 2, 3, 4, 5)
Bouyourou (by kurl)
Bettei Amafuru Oka
Yukyu no Yado Isshin
Ryokan Suiranrou
TAYUTA
Fufu Nara, Kyo Yunohana Resort Suisen, Fufu Kyoto, & Ryokan Onomichi Nishiyama (by OWHKG2016)
Takayamaso Hanano
Hiiragiya Ryokan
Jusandi
Takefue (by Hammerklavier)
Takefue & Yama no Chaya (by FlyingTurk1)
Kohanyu
Hotel Ridge
Hatago Wakatsu
Satoumitei Kinparo Hontei
Auberge Yusura