ONA
Description
Diana is a small, light gray or white-gray kitten who appears in the anime Pretty Guardian Sailor Moon Crystal. She is distinguished by her pink eyes, which closely resemble those of her charge, Chibiusa, as well as pale pink inner ears, whiskers, a yellow crescent moon mark on her forehead, and a light blue or lilac collar with a small yellow bell.

Her background is intrinsically linked to the future of the 30th century, where she resides in the kingdom of Crystal Tokyo. Diana is the only daughter of Luna and Artemis, the two guardian cats who serve the royal family of the Silver Millennium in the present day. In the future, she serves her primary role as the loyal guardian feline and companion to the Crown Princess, Chibiusa.

Diana's personality is presented as kind, thoughtful, and respectful, yet she also displays a determined and courageous spirit that belies her small size and young age. She is often seen as mature and responsible when the situation demands it, but like any young kitten, she can also show a playful and slightly mischievous side. Importantly, she is deeply loyal to the royal family of Crystal Tokyo, especially to King Endymion and Chibiusa, and is committed to protecting her home.

Her motivations are driven by a strong sense of duty and deep affection for her family and the future kingdom she calls home. When disaster strikes Crystal Tokyo at the hands of the Black Moon Clan, Diana is one of the very few individuals, along with Chibiusa, who remains conscious while others are incapacitated by a sleeping spell. Instead of fleeing to the past with Chibiusa, she makes the conscious decision to stay, refusing to leave the side of her unconscious parents, Luna and Artemis, and choosing to remain by the spectral form of King Endymion, determined to do whatever she can to save their homeland.

Diana's role in the story expands significantly during the crisis of the Black Moon arc. She acts as a source of information, providing crucial details to the king and the Sailor Guardians. In a moment of great importance, she even offers to temporarily take over the sacred duty of guarding the Space-Time Door from Sailor Pluto, allowing the latter to leave her post and join the final battle to save the future. This act demonstrates her bravery and her desire to contribute, even though she acknowledges she is tiny and has no powers of her own for combat.

Her key relationships are central to her character. The most significant is her bond with Chibiusa, to whom she is a devoted companion and advisor, always offering support and encouragement. She also shares a loving, if dutiful, relationship with her parents, referring to Luna and Artemis with respect and showing great concern for their well-being. Furthermore, Diana has a notable connection with King Endymion, staying by his side during times of crisis and offering him counsel. She is also an associate of Sailor Pluto, whom she assists by watching over the Space-Time Door.

Throughout the Black Moon arc, Diana's development is subtle but clear. She begins as a young kitten loyal to her family and quickly steps into a more proactive role, volunteering for a critical responsibility and proving her maturity and dedication to the future she is destined to protect. In later storylines, like the Sailor Stars arc, she demonstrates her profound bravery by traveling to the past to attempt to save her parents from danger, an act that leads to her being seriously injured.

Regarding notable abilities, Diana possesses the capacity for human speech like her parents. A significant power she shares with Luna and Artemis is the ability to transform into a human form in times of crisis. In this form, she appears as a young girl around Chibiusa's age, featuring her kitten's tail even as a human. Her most crucial responsibility, distinct from her parents, is her demonstrated capability to serve as the temporary guardian of the Space-Time Door, a task of immense importance in the Sailor Moon universe.