Sei-Lan holds the role of Instructor of Sensitivity, guiding the protagonist in controlling elemental forces. His expertise centers on Sacrea energies tied to Darkness, Water, and Dream elements—crucial for sustaining Arcadia's vitality and elevating its Happiness metric. Structured lessons under his tutelage directly enhance the protagonist's ability to wield these energies during cultivation.

Outside instruction, Sei-Lan engages in Arcadia's social rituals and festivals. He extends weekday date invitations featuring planned dialogues or gift exchanges, influencing his Intimacy and Respect metrics to unlock deeper narrative developments and collaborative ventures. His presence marks key cultural events like the Snow Prayer Festival and Night Wish Festival, where relationship parameters determine potential invitations. Unique illustrations during these occasions reflect narrative progression.

Relationship dynamics shape his arc: consistent positive interactions unlock romantic routes leading to multiple endings governed by Happiness, Intimacy, and Respect levels. Completing his personal events before a critical deadline is essential to access these conclusions. His affinity with other characters further enables specific collaborations during Arcadia's cultivation phases, emphasizing interconnected social systems.