There are four Sylvanian store in Shinjuku.
All stores are near from JR Shinjuku station west exit. (西口 means west exit)
Their English web sites are not available, sorry, please find the
locations of Google map.
Bic Camera Shinjuku (ビックカメラ)
1-5-1, Nishishinjuku, Shinjuku-ku, Tokyo Shinjuku west exit Hulk 2F - 7F
Keio department store 京王百貨店
in front of JR Shinjuku Station West Exit
1-1-4 Nishi-shinjuku, Shinjuku-ku, Tokyo
Yodobashi Camera Game Hobby bld. ヨドバシカメラ ゲームホビー館
1-11-1 Nishi-shinjuku, Shinjuku-ku, Tokyo
*They have some buildings, please ask store staff
Odakyu Department Store 小田急百貨店
1-5-1, Nishishinjuku, Shinjuku-ku, Tokyo
Odakyu Sightseeing Service Center Shinjuku will help you to go them.