Sakura Wars Kinematron Hanagumi Mail (サクラ大戦キネマトロン 花組メール) is mail software. Please note that it is not a game.
Description[]
The various expressions of the Hanagumi members have become stamps. Sends an email with a variety of bins. There are more than 60 kinds of stamps and bins in total. "Hanagumi Mail" can exchange mail with Dreamcast mail software, form phone mail service, and mail software for PC (text mail only). Both the sender and the recipient of this mail need this software to enjoy the visual effects such as stamps and bottles.