Some new information from her radio:

-Both Yonghwa and SWJA agreed the song has to be "warm". SWJA imagined 'Hello' to be an omnibus narrative: the two narrators in the song have two different experiences and memories they sing of. If you closely read the lyrics, the two aren't directly related with each other. Individual stories are coexisting in the song.

-Although she wrote 'Fireworks' thinking of Yonghwa and wanted to sing it with him, she was afraid to ask first because she thinks that she is not an artist who can guarantee commercial success. Right around the time she discussed this with her agency, Yonghwa approached her first with the offer. She was really surprised and thinks it’s not an overstatement at all to describe it as “fate” :)

-Yonghwa played the guitar for both ‘Hello’ and ‘Fireworks’. For ‘Fireworks,’ it just happened naturally on the day of recording Yonghwa’s vocals — there were many guitars lying around at the studio and he started playing with it. SWJA really liked the tune he played so asked him on the spot to record. Yonghwa, without his own instrument/pedalboard, willingly obliged and played hard to record for a long time. 

-The bridge part of ‘Fireworks’ was still incomplete, but Yonghwa played the piano and wrote all the chords/melody. It starts with “shining star, stained on your lips.” As soon as SWJA heard it, she thought “This is it!!” but Yonghwa humbly asked whether she’s just saying it as a compliment and requested to be honest. It wasn’t always easy for her to collaborate with other artists because she’s been working by herself for so long, but it was such a comfortable and assuring decision. She expressed thanks and was reminded of Yonghwa’s good composing skills.

-On Yonghwa’s “performance” of imitating ’Crow-tit’ (pulling the back of his head in Sketchbook), SWJA says she wants to try that at her next performance of the song. XD

-SWJA didn’t know much about CNBLUE’s musicality, but Yonghwa’s first solo album really smashed what she had thought before. When watching ‘Mileage’ MV, she says it was like finding a new musician. She likes how it sounds hiphop/pop, but has elements of Latin music. That led her to listen to all of his solo album and she realized what a sensible songwriter Yonghwa is. Towards the end of the show, she also recommends OFD as a really nice song and includes it in the playist. :D