My prediction that the title song of her upcoming single, Fuyu Hanabi / 冬花火 , is going to be an arranged song more on the heavy side now has more evidence that suggests it.
According to the description she wrote on the announcement at Excite Music, Fuyu Hanabi is a sad love song; the lyrics describe the feelings of a girl experiencing unrequited love, which are likened to fireworks: vivid, scattered/broken, and growing larger as time passes.
Funny, this reminds me of Kataomoi / 片思い (2005, vol.best) and Hatsukoi / 初恋 (2010, Hatsukoi / 初恋). She seems to have a thing for writing lyrics like these. Perhaps she writes from experience? The best works often come from the artist taking inspiration from a first-hand experience.
I may not be able to fully appreciate any of the lyrics she writes, but I can tell they are beautiful works of poetry.