Who is Initial "S"

"Wow? Don't you miss us? We didn't see each other last night. We were already asleep waiting for you to come home." Raja pulled up a chair and sat watching Putri, who had sat down and started staring at her computer screen.

"Oh, about last night? I've explained to Dad and Surya." Putri answered briefly.

Raja glanced at Rafa. "Hey.. this job seems to make you tired. Don't push yourself too much, Putri. How about we have lunch together." Rafa approached Putri.

"Maybe you should transfer to our department. The job isn't that hard. Did you see us?" Raja smirked.

Putri glanced at Raja, "I can't believe it with you. You guys never take work seriously and always tease female staff."

Rafa approached Raja and whispered, then the twins burst out laughing.