日向坂46メッセージ is a free iPhone app developed by Sony Music Solutions Inc. that allows users to connect with their favorite members of the Japanese girl group, Hinatazaka46. With the app, users can subscribe to their favorite members and receive exclusive messages, including photos and videos that are not available anywhere else. Additionally, users can send fan letters to their favorite members through the app, with the option to choose from pre-made templates for their messages.

The app also features a blog section where users can check the latest updates from the group's official website, with the option to receive notifications for new posts. The news section also allows users to stay up to date with the latest news from the group's official site, with the option to receive notifications for new articles. It's important to note that the talk feature is a paid monthly subscription service, and users will be automatically charged through their Apple ID. If users wish to cancel their subscription, they must turn off the automatic renewal at least 24 hours before the end of the subscription period.

Overall, 日向坂46メッセージ is a great app for fans of Hinatazaka46 who want to stay connected with their favorite members and receive exclusive content.