I was wandering create a list loke this one:

Cpt Hiroko
5 ronin
5 ronin
5 Hatamoto
5 Hatamoto
4 Demon Hunter
3 Tiger Dragon
1 Meka

Do you think it can be effective? Comments?

That's a lot of points to put into one Demon Hunter unit, but overall it could be effective. However, I'm curious if you have your points correct... with Ki powers and weapon options, that's essentially my 750 point list but with an additional 200 points of Demon Hunters. It looks more like a 1000 point list, and even then there's little room for Ki powers.

Surely points are not correc! What should I leave to remain competitive?

well, here's my 750 list for a slow-grow league we're running:

Hiroko (195)
5 Ronin (65)
5 Ronin (65)
5 Hatamoto, Blast of the Hurricane (95)
5 Hatamoto, Blast of the Hurricane (95)
3 Tiger Dragons, Dragonfire HMG, Blast of the Hurricane (81)
Meka (150)

Total 746

This list is restricted in that I have to use the starter set plus additional units, but there are a few options you can make. Firstly, consider if you're happy with Hiroko as your Warlord. He can be a little fragile if you don't keep him well out of the fight. Consider making a custom WL, and you can make adjustments to their points value from there. I suggest a psychic warlord if you like your shooting powers, but remember that you won't suffer Ki test penalties if you take all your powers from a single temple.
Build 1:
Demon Hunter Warlord (psychic), +1W, +2WP, Camouflage(2), Blast of the hurricane, Condensement of the Rainbow (150)
6 Ronin, Blast of the Hurricane (88)
5 Ronin, Blast of the Hurricane (75)
5 Ronin, Blast of the Hurricane (75)
3 Demon Hunters, Blast of the Hurricane (160)
3 Tiger Dragons, Destructive Path of Lava and Dragonfire HMG (91)
Meka (150)
Total: 799 points

This is all about using your Tiger Dragons and Ronin to get there fast, and back them up with the Demon Hunters and Meka.

Build 2:
Demon Hunter WL (CC), +2RoA, +1A, -1LD, +2ST, +1W, Leap(4), Ranger, Path of the Rat, Speed of the Horse (205)
5 Hatamoto, Speed of the Horse (100)
5 Hatamoto, Speed of the Horse (100)
5 Ronin, Stubborness of the Goat (85)
3 Demon Hunters, Prowl of the Tiger (160)
Meka (150)
Total 800

This is a force that should move together and hit hard when it gets to combat. With plenty of Speed of the Horse, those Hatamoto and your WL will be able to advance rapidly and still have an AP left to hide or shoot. Ronin, if they get there first, will be very survivable. The Demon Hunters can move through terrain with their Ki power as well.