五つ目の形態：日珥炎炎煉獄 in english letters, but not english language.
Its pronunciation would be "Nichi kaen-en-ren-goku" in Japanese.
Now, the full thing rather than the pronunciation.
The full thing, written in Japanese kanji characters, would be "日珥炎炎煉獄" which translates to "Scorching purgatory of blazing flames" in English.
this has "fifth form" added to it, right?
No, "fifth form" is not included in the original Japanese phrase "日珥炎炎煉獄". It simply translates to "Scorching purgatory of blazing flames".
Include "fifth form".
In that case, the full phrase with "fifth form" added to it would be: "日珥炎炎煉獄・伍ノ型" (Nichi kaen-en-ren-goku, Go no kata).
This translates to "Scorching purgatory of blazing flames, fifth form" in English. The "Go no kata" part means "fifth form" or "form five".
Reword this.
The user dashes forth at the target at blinding speeds and delivers a multitude of slashes onto the target, possibly amputating them if not killing them.