Saiarks are the main monsters of Happiness Charge Pretty Cure! and are made from the dark reflections of people's souls. They are usually summoned by the generals of the Phantom Empire when they find a likely victim. If the Cures fail to defeat the monster, the person can be stuck like this forever trapped in a dark mirror.
The monsters appear as large minions of the generals usually taking on a trait or two of the victims darkness. They wear sunglasses and scarves that have a certain color depending on who summoned it: green (Namakeruda), pink (Hoshiwa) or yellow (Oresky)and white (Phantom). There are also ones with bluish-gray scarves, but it is not known who summons those. Sometimes, they have different styles in any condition.
Choiarks (チョイアーク Choiāku?) are larger versions of Saiarks. They don't speak proper words, only using the word 'choi'. They wear all black with red sunglasses and white gloves and boots and always appear in groups.
- "Saiark" appears to be translated from terrible or worst.
- These are the first monsters to gain energy from humans, when they're having no negative feelings.
- This is the first season to have the monster already strong since the first it is appear and the Cures' way of defeating it is not simple.
- Namakeruda's Saiarks spread mold everywhere.
- Hosshiwa's Saiarks turn the environment into sweets and desserts.
- Oresky's Saiarks creates a dark cloud.
- Phantom's Saiarks turn the environment into amethyst mines.
- His also appear to have protrusions on their hands and different-looking sunglasses compared to the other Saiarks.
- The scarf on the Saiark shows which generals who summoned it (Namakeruda: Green, Hosshiwa: Pink and Oresky: Yellow, Blue (possibly Deep Mirror) and Phantom: White). Saiarks with blue scarves are more powerful, but that could be because the Cures's powers were weakened because of the strong presence of the Phantom Empire.
- They are the second monster who has different colour when one of the members summoned, preceded by Nakewameke.
- Similar to Jikochuu, they are summoned without fusing an objects.
- They're some-what similar to the Heartless from the Kingdom Hearts series.