'Hello' was my first thought so here are some Hello songs.
Nu'Est SHINee Aprince B.I.G Boys Republic Yoo Seung Woo HuhGak
Fiestar BOA RaNia Hyosung Romeo Strawberry Milk Hello Venus BTOB Got7 GD feat Dara Akdong Musician Hani Ryeowook
My favourites are Ryeowook, BTOB, Aprince and SHINee