There are four ways to acquire fireworks and I shall outline them here:
1) Win battles in Coliseum - you can win 2x, 3x or 4x Fireworks depending on
enemy you fight (not recommended for sake of walkthrough).
2) Four chocobogirls in Yusnaan for 1x Fireworks per girl, between 7PM-3AM. But
before you can get the goodies from the females, you must examine one poster
that advertises a special reward. The poster I recommend examining is the
one closest to chocobogirl in the back alley. Not only will it allow you to
get Fireworks, you also get key item [*???] needed for Canvas of Prayers
quest. Chocobogirls' locations are as follows.
- In the back alley.
- Near weapon shop in shopping arcade.
- Near armor shop in Gastronomy area.
- Near the guardpost at train station.
After you get Fireworks from fourth chocobogirl, she also awards you with
Miqote garb (the best victory fanfare when you win).
3) Go to four blue "!" and talk to technicians there to get some fireworks.
- Technician near Cactuar statue gives 3x Fireworks, between 7PM-10:30PM.
- Technician on Central street needs some sake, for which you must complete
YSQ "Drunken fireworks", between 7PM-11PM. Upon execution you get 4x
Fireworks. THIS IS YOUR ONLY CHANCE TO DO THIS SUBQUEST.
- Technician near Coliseum gives 3x Fireworks, between 7PM-11:30PM.
- Technician near train station gives 2x Fireworks, between 7PM-12PM.
4) Complete a MISSABLE YSQ "Fireworks devil" for 7x Fireworks.