when you start to feel a mix of horniness and excitment from your allocated senpai.
"omg she was walking down the hallway with her senpai and she was lowkey in s - phase"

(S-phase person): "omg uwu senpai you make me so emoshi and creami thx." "can i have kwisses and cwuddles pwease kitten"
by Shaonika March 21, 2022
Get the s - phase mug.
the moment in which you feel a mixture of horniness and look up to your senpai, performing anime like movements and expressions.
omg i saw her down the hallway and shes literally in s - phase. she called me senpai before. uwu.
by Shaonika March 18, 2022
Get the s - phase mug.