Here is the full list of all 35 Dark Samurai Demo achievements.
Upgrade Katana Slash Attack Damage 8 times in a single run
Upgrade Katana Slash Combo 8 times in a single run
Upgrade Katana Slash Focus 8 times in a single run
Upgrade Katana Spin Attack Damage 8 times in a single run
Upgrade Katana Spin Attack Speed 8 times in a single run
Upgrade Katana Spin Clone 8 times in a single run
Upgrade Yumi Shot Attack Damage 8 times in a single run
Upgrade Yumi Shot Flurry 8 times in a single run
Upgrade Yumi Shot Focus 8 times in a single run
Upgrade Yumi Shot Piercing 8 times in a single run
Upgrade Yumi Shot Spray 8 times in a single run
Upgrade Katana Slash 100 times total
Upgrade Katana Spin 100 times total
Upgrade Yumi Shot 100 times total
Upgrade Yumi Snipe 100 times total
Upgrade Yumi Voilley 100 times total
Upgrade Shuriken Fan 100 times total
Upgrade Grenade 100 times total
Visit Shikoku
Survive 10 minutes on Shikoku
Survive 20 minutes on Shikoku
Survive 30 minutes on Shikoku
Survive 10 minutes as Samurai
Survive 20 minutes as Samurai
Survive 30 minutes as Samurai
Survive 10 minutes as Archer
Survive 20 minutes as Archer
Survive 30 minutes as Archer
Discover the Katana Slash attack
Discover the Katana Spin attack
Discover the Yumi Shot attack
Discover the Yumi Snipe attack
Discover the Yumi Volley attack
Discover the Shuriken Fan attack
Discover the Grenade attack