Cafe Seiren is a common meeting place for members of the cast to gather for social outings. Events of both the main storyline and various side stories take place within it. It is also possible to visit the cafe at will, where Itsuki can order an item from either the food or drink menu to restore the party's health and give luck boosts to individual party members.
The waitress that serves Itsuki when he visits Cafe Seiren for food or drink resembles Ilyana of Fire Emblem: Path of Radiance and Radiant Dawn. The waitress offers side quests to Itsuki that consist of bringing her ingredients for experimental new menu items. When the side quests are completed, the new items are added to the menu and can be ordered like the standard menu items.
In the real Shibuya, where this cafe lies, is the cafe franchise that Cafe Seiren is based on, Starbucks.