Ginga Kankou Ryokan - Chuu no Yu he Irraishai

is a Japanese light novel series written by Ryuji Arai, with illustrations by Nankotsu Misakura. The series began publication on November 10, 2001 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
Sansuke Atami, who lives in the idyllic hot spring town of Hamaki Watasaki, is an ordinary high school student, except that he is a good person. Suddenly, a mysterious trouble came to Sansuke. Luca Sorano, a beautiful girl who has transferred to Sansuke's class, insists that she is a childhood friend of Sansuke. Sansuke, who can't remember anyway, sneaks into Luka's parents' home, the "Sora no Yu Ryokan", a long-established hot spring inn that suddenly appeared in front of the station. What Sansuke saw there was ... A sci-fi comedy about the happy daily life of a boy who has learned the secrets of the Earth branch of the galaxy's weak travel agency.

Light Novel Volumes
銀河観光旅館　宙の湯へいらっしゃ～い！
 * Ginga kanko ryokan 1.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai!

''Welcome to Sora no Yu, a galaxy tourist inn! 銀河観光旅館　宙の湯へいらっしゃ～い！（２）
 * November, 2001
 * Ginga kanko ryokan 2.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (2)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (2)

''Welcome to Sora no Yu, a galaxy tourist inn! (2) 銀河観光旅館　宙の湯へいらっしゃ～い！（３）
 * July, 2002
 * Ginga kanko ryokan 3.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (3)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (3)

''Welcome to Sora no Yu, a galaxy tourist inn! (3) 銀河観光旅館　宙の湯へいらっしゃ～い！（４）
 * November, 2002
 * Ginga kanko ryokan 4.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (4)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (4)

''Welcome to Sora no Yu, a galaxy tourist inn! (4) 銀河観光旅館　宙の湯へいらっしゃ～い！（５）
 * May, 2003
 * Ginga kanko ryokan 5.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (5)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (5)

''Welcome to Sora no Yu, a galaxy tourist inn! (5) 銀河観光旅館　宙の湯へいらっしゃ～い！（６）
 * August, 2003
 * Ginga kanko ryokan 6.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (6)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (6)

''Welcome to Sora no Yu, a galaxy tourist inn! (6) 銀河観光旅館　宙の湯へいらっしゃ～い！（７）
 * January, 2004
 * Ginga kanko ryokan 7.jpg
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (7)
 * Ginga Kankou Ryokan - Chuu no Yu he Irraishai! (7)

''Welcome to Sora no Yu, a galaxy tourist inn! (7)
 * June, 2004
 * }