As a trainee Tzuyu had seen Sana repeatedly, knew of her existence on some levels. Sana had also heard of Tzuyu but never talked to the girl directly until their debut as the JYP girl group Twice. 

Tzuyu was woken up by Sana one morning for a girl's day out,  all of them going on a beach trip, but she didn't expect lil Sana to lay on top of her, legs sprawled on either side of Tzuyu's, hands rested above her head. "SANA! HOW LONG HAVE YOU BEEN THERE!"  
"About a minute. You weren't waking up at the sound of Jihyo shouting at Momo for eating the last instant ramyeon and then demanding more food. Again." 

"Well I'm awake. You comfortable there?"

"Yep. Maybe I should get a Tzuyu shaped bed." She winked and ran off as Tzuyu rolled out of bed onto the floor where she had left a couple of bean bag chairs to catch herself. Unfortunately she had yet to perfect this idea as she always bounced right onto the floor from the bean bags and it hurt. She hurriedly dressed as she heard an incensed Jihyo stomping down the corridor. "TZUYU YOU BETTER BE UP OR I WILL FREAKING WHOOP YOUR !"

"I'M UP DON'T HURT ME!"

"Ha ha you funny. Move it I'm already about to kill Momo. She will not stop eating any food. I might buy a lock for the cupboard and fridge and tell everyone the combination except Momo. . . Or Mina."

Mina? Mina eats a lot but not Momo sized portions. I eat more than Mina. 

Tzuyu shrugged it off and got everything she needed and ate breakfast waiting for Jihyo to signal to everyone to get in the car. Sana flopped next to Tzuyu and stole the last bite of her food. "I should have known. You came for the nut cereal not me squirrel human." Sana laughed at Tzuyu's indignation and put her head on her shoulder. "Do you forgive me Tzuyu?" Tzuyu felt butterflies as Sana's head rested on her shoulder. "How could I not?" she murmured softly, seeing the twinkle in Sana's beautiful eyes for the first time, the way her luscious lips curved while she laughed. . . 

Snap out of it! She told herself. Sana laughed again at her response and linked their arms as Jihyo ushered everyone into the minivan. Sana hung onto Tzuyu's arm and say next to her in the van, chatting away happily and resting her head on Tzuyu's shoulder periodically. Tzuyu was hot under the collar as this played out, not knowing what the hell was going on in her stomach. Why do I feel like this? Am I sick?