There seems to be a lot of computer games for MSX1. 'Knight Leon' is one of them.
I got a used MSX micro (Ano III Nº17) magazine that is about database and there is previews of new games. Hype, Knight Leon and MASTER OF THE UNIVERSE (HE-MAN). The other articles were about talking in machine language to the MSX, Programs Color on DOS, Artificial Intelligence . Super Games: Jack the Nipper I and II.

Knight Leon

Yami no ryu ou Hades no monshou (Crest of the Dragon King Hades of Darkness)

I used to know this game by the game of "Leonidas Odyssey". It's a good clone of knightmare

It is a good one to be mapped

So, it's Casio's "Yami no ryu ou Hades no monshou (Crest of the Dragon King Hades of Darkness)"... does someone have a box scan or something else that shows that it was also released under another name (something with Leon)?

Probably not, Manuel. But here in Brazil was quite common to some softhouses to sell pirate copies of japanese games with new names invented by them (since few people know japanese around here). So we had many games with names completely different from their original meanings... Perhaps some of these fake names spreaded...

Mokarimakka - Animal Basket
Chima Chima - Graveyard Cemetery
Yami no Ryu Ou - Knight Leon

In Konamito's page you can find the review published in a popular MSX magazine here in Spain. By some reason they call it "Leonidas Odyssey"....

"Leonidas Odyssey" Input MSX's review

Indeed! Very odd...