Mini Conversations
From A3! Wiki
Mini Conversations (ミニ会話) are short dialogues which can be activated by playing through a Practice Mission by meeting certain conditions. Each practice mission partner will have 3 short dialogues with the player, and one short conversation with them and another character. In general, the first dialogue will be self-reflective, the second will focus on another character, and the third will be about the Director.
As of the May 31 2019 update, players can use Magic Bookmarks to unlock Mini Conversations from events.