LAOX is a leading company in offering Muslim-friendly services all across Japan, including Muslim-friendly tax-free souvenir shop counter and prayer spaces.
https://halalmedia.jpsouvenir-muslim-laoxtax-free/
LAOX Nagoya Maruei now has a prayer space(7th floor) available. It is free to use by anyone, including non-shoppers.
*The souvenir shop counter is not HALAL-friendly.
http://www.laox.co.jp/en/stores/nagoyamaruei/