I emailed them in English.
Try this:
shop.mu-mo.net/q/index.htmlClick on any of the F.A.Qs' link, any will do.
Then click on the the button within the blue box which says お問い合わせフォームへ to enter the contact form page.
Click on the button on the next page.
Then you will come to the contact form page:
お名前(必須)(Your name, in English will do)
メールアドレス (半角英数) (必須) (Your email address)
メールアドレス (確認のため) (必須)(Confirm your email address)
日中連絡先電話番号(必須)Contact number, I put my real number despite being from Singapore)
電話番号(Secondary contact number, not necessary, I left this blank)
住所 (Address, left it blank)
会員ID (Your mu-mo membership ID)
お問い合わせ内容(全角125文字まで) (必須) (This is where you tell them your problem. Just tell them you bought the item (name) with the link provided, but you did not receive the lottery code.
購入場所 (Where you bought the product, select mu-moショップ)
ご注文日時または会場購入日 (Month / Date / Time *Respectively* when you ordered the album)
購入会場名(会場購入の場合)(Left this blank as it asked for the venue of the album purchased)
注文番号 (Key your order number here, eg 1254xxxx)
商品番号・商品名(Item number and name, if you bought the DVD version just paste this AVCT-10186A - Best moves.(AL3枚組+DVD))
お支払い方法(Payment method)
Choose the first one ( カード) if you paid by card.
This is the procedure I did to exactly. Hope it helps.