Hand Friend

Chapter 2: Let's Hold Hands in Secret
Chapter 1.5: Episode 0
Chapter 2.5: Episode 0.5
Chapter 1.5: Episode 0
Chapter 2.5: Episode 0.5
Kagura already has a girlfriend. But Hosoya, the girl who sits next to Kagura, offers him a "tefure" relationship. What kind of relationship is this?