While I'm aware that there are translations and roomajis floating around the internet for J's works, I'm also keeping in mind that his artistic name is a simple letter - and thus making it quite hard when it's time to dig for info.
So! I decided to start a J archive of roomaji lyrics, too. I might not work so hard on this because there are other sources, but I'll definately give a hand to the fandom (I'm actually thinking of translating his "Words" into English from their French translation). I'll give preference to songs from his new album "ON FIRE", since it's new and less likely to have roomajis ready.
fire
(fire on your mind
fire on your love)
Kurayami wo kirisaite
Akai tsuki ga noboru yoru
Subete wo kowashite
Subete ga umareru
Atarashii rekishi no hajimari ima
Moyase fire on your mind
Terase fire on your love
Kuruoshii hodo kono ima wo shinjite
Moyase fire on your pride
Soshite fire on your all
Te ni shitai mirai nara ubaeba ii
Iiwakesae tojikomete bouhatsu suru taiyou
Dareka ga warai
Dareka ga naku yoru
Sekai ni hi wo tsukete ima
Moyase fire on your mind
Okose fire on your life
Hokorashii hodo jiyuu wo kanjite
Moyase fire on your ground
Soshite fire on your all
Tomaranai jidai sae kaeteyuke
Subete wo kowashite
Subete ga umareru
Atarashii rekishi no hajimari ima
Moyase fire on your mind
Terase fire on your love
Kuruoshii hodo jibun wo shinjite
Moyase fire on your pride
Soshite fire on your all
Te ni shitai mirai nara ubaeba ii tonight
Moyase fire on your mind
Okose fire on your life
Hokorashii sono honoo wo kanjite
Moyase fire on your ground
Soshite fire on your all
Kudaranai jidai sae koeteyuke