Italics will be used when they are speaking in English. 

A Friday night with no work and nothing better to do, Taemin had gone over to Kai’s house where the two did the only activity that made sense. Practice their English.

“Hello. My name is Taemin. It’s nice to meet you,” Taemin said is his careful, practiced English.

“Hello, Taemin. My name is Kai. It’s nice to meet you too.”

“How are you?”

“I’m fine, thank you. And you?”

“I am fine as well. What are your hobbies?”

“I like to dance and juggle. What are your hobbies?”

“I like dancing and playing.”

“What kind of food do you like?”

“I like eating banana milk.”

“Hyung, that’s a drink! What’s something you like eating?” Kai corrected switching to Korean, laughing at his friend’s mistake.

“Oh, uhh…,” Taemin thought, “I like meat and fruit. What food do you like?”

“I like many food.”

“I think you add an ‘s’ sound at the end of ‘food’ because there’s more than one food.”

“Aish, there’s a reason I’m taking Japanese…”

“You need to practice English to though.”

“But I don’t want to!”

“How old are you?”

“I am seventeen years old. Why?

“You are a baby.”

“….Did you call me a baby?”

“No, I called you a man.”

“Oh, thank you!”

“Stupid.”

“That’s not very nice, hyung….”

yeah not much description in this chapter. Hopefully you didn't get lost while reading it.