This adds a brand-new recipient of your data. When you use the site, your browsing history and device information go to SoftBank, a mobile phone company, so that ads can be aimed at you more precisely. Even though the site says it does not send your name or other directly identifying details, a carrier can often connect an IP address to a real subscriber account, so this links what you read on the site to a person's phone service.
“本機能により、当サイトからソフトバンク株式会社へ、デバイス情報(国・地域情報、通信環境等)および履歴情報(閲覧履歴等)が送信されますが、ユーザーの個人情報を送信することはありません。”
What you can do — If you don't want this, use the opt-out page at https://www.softbank.jp/privacy/personaldata/utilization/ads/ . You can also check your SoftBank account settings, since the program only covers users who agreed to data use there.