Susukihotaru confides in Zakuro that she is intimidated by the size of her new partner Riken. Later when Riken sees Susukihotaru struggling to reach a high shelf he picks the item up for her and kneels before her, sincerely asking if this made her feel more comfortable.
Ganryu being able to tell Hozuki and Bonbori apart soon after being assigned to the Unit. This clearly delighted the twins to no end and helped to set-up Ganryu as being more insightful than anyone realized.
The scenes near the end of Episode 4 between Riken and Susukihotaru: silent empathy powered Love Confession!