From the way Meifumado ( 冥府魔道) gets thrown around by the characters of Lone Wolf and Cub it seems that Meifumado is a well established concept in Japanese culture. It’s not. Koike created the term specifically for Ogami Ittos quest for vengeance. In the Glossary of the Dark Horse volumes it is explained as “The Buddhist hell, the way of demons and damnation”.

As is often the case in the dark horse translation, the word gets an English explainer after it is used. Similar to saying anime animation or manga comics, but the translators have generally seem to have found a rhythm to it and seems natural enough. Here Meifumado is generally expounded as the road to hell or the demon way to hell. With the latter being a fairly literal translation

Meifumado is a compound of two existing words, Meifu ( 冥府 ) and Mado ( 魔道 ). Meifu refers to a sort of underworld, translating to realm of the dead; hell. It has a synonym Jigoku ( 地獄) Which has a more direct connection to a specifically Buddhist Hell. It seems that Meifu is an archaic term borrowed up from the earlier Shinto beliefs and not a direct match for Hell. Much like how places such as Hades, the Abyss and Pandemonium are similar to, but are separate and distinct from the christian Hell.

Mado (魔道) translates to several interrelated concepts. Most clearly as, a way of life characterized as evil or heretical, but also as sorcery, black magic and netherworld outside the six realms where evil spirits roam. Mado also breaks down into two separate words, Ma and do. Ma (魔) meaning witch, demon, or evil spirit. Do (道) is the same as that which appears in bushido (way of the warrior). Giving a literal translation of way of the demon or demon way. It should be noted from this that to take up Mado is also a renunciation of Bushido (Ittos actions aside).

I need to do more research into the cultural specifics of Meifu before deciding, but it seems that Road to Perdition is a very accurate title for the comic that adapted the general idea idea of Lone Wolf and Cub. Perdition being a another particular version of Hell, with the additional (although sadly archaic) definition of utter destruction.

Definitions sourced from wikitionary and https://jisho.org/.

“THOUGH WE BECOME THE DEMONS OF MEIFUMADO! THOUGH WE CLAW FLESH AND DRINK BLOOD, REDUCED TO BONE WE WILL TRANSCEND THE 6 PATHS AND THE FOUR LIVES!” – Ogami Itto to Yagyu Retsudo, fiftieth chapter: The Yagyu Letter.