Affection is a mechanic that gauges the heroines' bond with Takt and influence the efficiency of Takt's Support Ability.
The Affection menu option allows you to check the heroine's affection toward Takt. You can gauge her current level of affection by judging her facial expression as well as the thickness of the line connecting her to Takt. For every level of affection reached, the heroines will have different things to say when you select them and press square. There are a total of 5 affection levels.
Pairing up with a heroine that has a high affection level will increase Takt's Support Ability, and the pair's stat increases will rise even further.
Affection can be increased by viewing character events around the Office or town, by winning battles with Takt paired to a particular Verse Maiden, or by using Takt's Paired and Group Defense actions to protect the Verse Maidens during battle.