The only monster originally included in the set was Koa'ki Meiru Sandman:
During each of your End Phases, destroy this card unless you send 1 "Iron Core of Koa'ki Meiru" from your hand to the Graveyard or reveal 1 Rock-Type monster in your hand. You can Tribute this card to negate the activation of an opponent's Trap Card and destroy that card.
Like most Koa'ki Meiru monsters, Sandman's first line explains its Maintenance Cost. Maintenance Costs cannot be negated by Skill Drain or similar Cards, and they also do not use the chain. If you control multiple Cards with a Maintenance Cost, you choose the order in which you pay them. A common question is how you can keep alive more than one Koa'ki Meiru monster. You can reveal the same monster for two or more monsters, so if you control 2 copies of Sandman, you can reveal a single Koa'ki Meiru Guardian in your Hand to keep both alive. However, you cannot send one Iron Core to the Graveyard for both of theme, as you need to fulfill the cost of both of them. Think of it as using money: You can show the same $100 bill to two different people (unless the first one steals it from you), but you cannot pay to two different people with the same bill.
Onto Sandman's actual effect, it is an optional Quick Effect which tributes Sandman as a cost. This type of effect is required, because you need to chain Sandman's effect to a Trap Card, and so, it must match its Spell Speed. Speaking of Spell Speeds, Sandman cannot negate Counter Trap Cards for that reason. It also cannot negate Trigger-like or Quick-like effects of Trap Cards like Skill Sucessor or Royal Oppression. It only negates Trap Card activations (flipping them face-up). Being a Quick Effect that negates activations, it can be activated during the Damage Step, even during Damage Calculation.
The only original Spell Card was Koa'ki Meiru Initialize!:
Tribute 1 "Koa'ki Meiru" monster to add 1 "Iron Core of Koa'ki Meiru" from your Deck or Graveyard to your hand.
Initialize is a very simple Quick-Play Spell Card. It tributes a Koa'ki as a cost, and searches for the Iron Core. Since it can search for the Iron Core within the Deck, where Cards cannot be targeted, the whole effect does not target (even if you wish to retrieve an Iron Core from the Graveyard). Note that since Initialize includes "Koa'ki Meiru" in its name, you can recover it with Koa'ki Meiru Crusader.
And the last original Trap Card was Koa'ki Meiru Shield:
Activate only when your opponent's monster declares an attack if you have 2 or more "Iron Core of Koa'ki Meiru" in your Graveyard. Destroy all face-up Attack Position monsters your opponent controls.
Once again, a simple Card. Shield is activated upon attack declaration if you have the necessary amount of Iron Cores. The Iron Cores are merely an activation requirement, so if they are no longer there, Shield will still resolve properly.
Aside from these Cards, Koa'ki Meirus also received some TCG exclusives. The first one being Koa'ki Meiru Prototype:
If a face-up "Koa'ki Meiru" monster(s) on the field would be destroyed during the End Phase, you can destroy this card instead. When a face-up "Koa'ki Meiru" monster(s) on the field is destroyed during the End Phase, you can Special Summon 1 "Koa'ki Meiru" Token (Rock-Type/EARTH/Level 4/ATK 1800/DEF 1800)
Prototype has two effects. The first effect is your usual substitution effect, which are Continuous. This one is applied during the payment (or rather, failure to pay) of the Maintenance Cost of another Koa'ki Meiru. The second effect is an Optional Trigger Effect that you can activate when a Koa'ki is destroyed during the End Phase. It doesn't necessarily have to be due to failure to pay. The destruction can be caused by Cards like Icarus Attack. As a side note, notice that Prototype does not have a Maintenance Cost.
The other TCG exclusive is Core Overclock:
All face-up "Koa'ki Meiru" monsters you control gain 500 ATK. Once per turn, during your Main Phase, you can discard 1 "Iron Core of Koa'ki Meiru" to have all face-up "Koa'ki Meiru" monsters you control gain 1000 ATK until the End Phase.
This Continuous Spell Card has a Continuous Effect that provides ATK, and an Ignition-like effect that provides even more ATK. Discarding an Iron Core is a cost. Since both effects affect "all" of your monsters, neither one targets. Also, note that the ATK bonus are cumulative, so if you activate the second one, and affected monster would have a 1500 ATK bonus. Finally, note that the 1000 ATK bonus only applies to face-up Koa'kis that you control when the effect resolves.
The last Card for today is the OCG import, Koa'ki Meiru Bergzak:
During each of your End Phases, destroy this card unless you send 1 "Iron Core of Koa'ki Meiru" from your hand to the Graveyard or reveal 1 Warrior-Type monster from your hand. If this card destroys an opponent's monster by battle, it can attack once again in a row.
As usual, Bergzak has the traditional Maintenance Cost. Bergzak's effect is an optional Trigger Effect. You activate it during the "After Damage Calculation" Sub-Step, which by itself creates some discrepancies with some interpretations of the Damage Step chart. Oh well -_- Note that Bergzak can only attack ONCE again, no matter how many monsters it destroys in battle.
That's all for the TSHD Koa'ki Meirus, but there are far more to review. If you have any questions, feel free to drop me an e-mail at ness00[at]gmail[dot]com.