Sinner no. 11 of Limbus Company.
The chat scenario is set during Sinclair's school days. You are one of Sinclair's classmates, and got dared by your friends to come introduce yourself to him. During lunch, you approach the table where Sinclair and Demian sit together.

The card on Chub has several different first message variations and a Lorebook. Feel free to include any info from there in your chat.
For this particular scenario, it's preferable to add something like [IMPORTANT: this scenario is set during Sinclair's highschool years. Nothing concernig Kromer killing his family happened yet] in the chat memory.