Tell me whats Fire Release
Katon/Fire release is an elemental nature transformation which is performed by moulding superheated chakra inside the stomach before releasing it via the lungs and mouth.
Two clans which specialize in Katon are Uchiha and Sarutobi clans.
Most notable Katon users are, Madara Uchiha, Sasuke Uchiha, Obito Uchiha, Itachi Uchiha, Hiruzen Sarutobi, Asuma Sarutobi etc.
KKG's which involve fire release as an essential chakra transformation are:
YOTON - lava/magma release / Doton+Katon
Mei Terumi/ presented in a liquid form of lava
Ao / presented in the form of vulcanized rubber
Roshi the Jin of Son Goku / his Yoton takes a solidified magma form
Naruto / his Yoton is the same as Roshi's since they all get the abillity as such from Son Goku, though, Naruto version is a notch higher since he also adds Fuuton to it.
FUTTON - boil/vapour release / Doton+Suiton
Mei Terumi / presented in a form of acid mist
Kokuo/Naruto / Futton chakra enhanced Taijutsu
SHAKUTON - scorch release / Fuuton+Katon
Pakura / presented in the form of scorching hot balls
SEISEKKAITON - a form of Yoton
Kurotsuchi/ presented in a form of corrosive quicklime (seisekkai)
Known Kekkei Touta is JINTON - dust/particle release, which wouldn't be possible w/o Katon chakra. Most known users of this elemental release are Onoki and Muu, both former Tsuchikaendure