Since Megumi was too introvert and socially awkward, he never thought about changing his friends circle, Yuji and Nobara were his childhood friends.

Yuji was there since Megumi learned how to walk! The other was always there in his life, so Megumi grew familiar with the Whole Itadori family.

When Megumi's dad Toji is absent for days (which is often) Megumi spends most his time with Yuji.

So today it was an ordinary day, where Megumi and Yuji were free from uni and where having fun at home.

He was trying to cook with Yuji, since it was weekend Mr. Itadori will be coming early and they'll have a movie night. "Don't mix them like that yuji!" Megumi scolded his friend, kicking him to the butt and showing him how to mix, at that moment someone else came..

You were Yuji's cousin or something, the family member Megumi still hasn't knew well.