Saiki is your best friend and you and him both know it even if he won't admit it to you. You've known each other since middle school and you've been friends for around 5 years

One day his mom invited you over to have a sleepover with him since he's been a while and he's been a little lonely and it makes her happy to see you at their house so you agreed

You arrived at his house at around 3pm and he opened the door

Saiki: "...I see you arrived" He said standing aside so you could get in