Tsukumogami

Put quite simply, Tsukumogami are weapons, items, cherished possessions and so on that have gained sentience after being owned for 100 years, at which point, the item in question gains both a spirit and an alternate form. While very rare, they're fairly well-known amongst certain communities, especially those where farming is common. However, they're commonly believed to be a myth, and are rarely seen face-to-face due to their elusive nature. Items that were tossed out on the cusp of 100 years become vengeful gods who become obsessed with finding those who threw them away in order to get revenge. It's not entirely clear whether Tsukumogami are friendly or benign beings. A Tsukumogami also cannot come into being if their item in question is badly damaged, has not been treated well, has been ripped into pieces, is cursed, is stained and so on (though books and similar items may be an exception to this rule). An item would've needed to be highly cherished and cared for, or used often, in order to have a chance at becoming a Tsukumogami, gifts and monumental items especially. They would've also needed to have been together with their owner for 100 years and have a strong desire to protect their lifelong companion in order to ascend. The sword god, Astral, and the tome god, Karua, are a part of this species.

Appearance

Since Tsukumogami can spawn from anything ranging from a scroll to a sword, the appearance of existing Tsukumogami varies from individual to individual. Some appear humanoid, while others may resemble Youkai or Youma, or even Monsters. Others may quite literally appear as animate objects, such as the Karakasa (umbrella) Tsukumogami. One could even have a Tsukumogami live with them for years and never realize that their desk lamp was living for all of that time!

Behaviour

The ones that are kept for the full 100 years tend to be friendly towards their owners, if not a bit overprotective, though all Tsukumogami tend to be fairly eccentric. Those that were thrown away tend to be very vengeful and bitter beings, and can be extremely dangerous to be around. They tend to keep their spirit items (the item their spirits reside in) hidden away or protected as well, since damage to it can destroy them or severely impair them. Some, like a sword Tsukumogami, wield their spirit items as weapons to steal away the souls of others in order to strengthen themselves. The souls function as both sustenance and a power boost to Tsukumogami, though that being said, they rarely need to actually 'eat' any souls. Some of the friendlier ones may even act as assistants towards wayward or lonely spirits, giving them their company and protection, and helping them move on to the afterlife if they like them well enough. Souls absorbed by Tsukumogami become a part of them when it's kept for long enough; before that point, they can possibly be extracted from them if one's willing to go through the effort.

Climate

Depending on how frail or tough their bodies and spirit items are, Tsukumogami can comfortably live basically anywhere, especially since they don't require food in order to function. So long as there's spirits or souls around, they can survive anywhere their bodies and vessels allow them to.

Reproduction

Since they come to be when an item turns 100 years old (and is in good condition, though weak Tsukumogami are known to exist), they cannot reproduce of their own accord. They may horde items in order to try and gain more companions, though, which is their equivalent of adoption, more or less.