Illusory Faith

The Focus Shot of Reimu Hakurei, who has almost reached the end (a Touhou LW original). Sentient tools are shot out from her Armored Yin-Yang Orbs in this attack.

The Inheritor of the Yin-Yang Orbs
Reimu Hakurei is the inheritor of the Yin-Yang Orbs, and it's said that only those of the Hakurei clan bloodline can use the orbs. They are used to exterminate youkai, and Reimu is known to carry them with her whenever she sets out to resolve an incident.

Misumaru Tamatsukuri claims to be the one who created the Yin-Yang Orbs, so it's possible she's familiar with the Hakurei clan's history. If the Hakurei shrine maiden is a hereditary title, it begs to reason that the orbs have been passed down with it. Assuming that's true, the earliest members of the Hakurei clan may have been brave youkai-exterminating humans in the time before Gensokyo was established. Then, after it was established, they would have moved to Gensokyo with the aim of controlling the youkai. From then on, they would have fought against the youkai every night until, eventually, they were trapped in Gensokyo along with the youkai when the barrier was formed.

The Yin-Yang Orbs continuously absorb their user's power, and when enough has accumulated, they release that power in an instant, whereupon the cycle starts again. It's rumored that the orbs are so powerful that if they were to fall into the wrong hands, they could destroy the entire world... but the origins of this rumor are unknown.

Similar to the Yin-Yang Orbs, the dragon gems are also Izanagi Objects, and they have the trait of replicating their user's ability, giving some credit to the aforementioned rumor. On the other hand, the orbs also display many similarities to the Miracle Mallet, an oni item. Furthermore, the orbs strongly resemble wheel-like creatures that have been sighted within the borders of Gensokyo, but it's unclear what connection, if any, they have with the orbs.