Walkthrough
http://seiya-saiga.com/game/navel/tsukioto2.html
Website(s)
https://www.ec-order.com/navel/shop/detail/NVL0000145
https://www.ec-order.com/navel/shop/detail/NVL0000144
http://project-navel.com/tsukiniyorisou_2nd/index.html
http://project-navel.com/tsukiniyorisou_2nd/spec.html