Update purchase button text to Japanese for localization

Author: shunk031

themes/influencer-hugo/layouts/partials/header.html

@@ -37,12 +37,14 @@ <h2 class="mb-0 text-color">{{ .Site.Title }}</h2>
 
         {{ if .Site.Params.navButton.enable }}
         {{ "<!-- nav btn -->" | safeHTML }}
-          <button class="snipcart-add-item btn btn-border-tp btn-small ml-0 ml-lg-3 mb-3 mb-lg-0" data-item-id="1"
-          data-item-name="{{ .Site.Data.homepage.banner.title | markdownify }}" data-item-image="{{ .Site.Data.homepage.banner.image | absURL }}" data-item-price="{{ .Site.Data.homepage.banner.price }}" data-item-url="/">
-          Purchase now
+        <button class="snipcart-add-item btn btn-border-tp btn-small ml-0 ml-lg-3 mb-3 mb-lg-0" data-item-id="1"
+          data-item-name="{{ .Site.Data.homepage.banner.title | markdownify }}"
+          data-item-image="{{ .Site.Data.homepage.banner.image | absURL }}"
+          data-item-price="{{ .Site.Data.homepage.banner.price }}" data-item-url="/">
+          購入はこちら
         </button>
         {{ end }}
       </div>
     </div>
   </nav>
-</div>
+</div>