Your page does not have a viewport specified. This causes mobile devices to render your page as it would appear on a desktop browser, scaling it down to fit on a mobile screen. Configure a viewport to allow your page to render properly on all devices.
Size tap targets appropriately
Some of the links/buttons on your webpage may be too small for a user to easily tap on a touchscreen. Consider making these tap targets larger to provide a better user experience.
The following tap targets are close to other nearby tap targets and may need additional spacing around them.
The tap target <a href="/fmt/about.shtml">「住む。」について</a> is close to 1 other tap targets.
The tap target <a href="/numbers/">最新号紹介</a> is close to 1 other tap targets.
The tap target <a href="http://online.…?item_code=116" class="topurchase">購入する</a> is close to 1 other tap targets.
The tap target <a href="http://sumu.sa…mbers/64.shtml" class="todetail">詳細はこちら</a> is close to 1 other tap targets.
sumu.jp Mobile Speed: 65/100
sumu.jp Mobile Speed Test Quick Overview
Leverage browser caching
Setting an expiry date or a maximum age in the HTTP headers for static resources instructs the browser to load previously downloaded resources from local disk rather than over the network.