"Depressing" and "traumatic" are subjective terms, and what affects one person emotionally may not have the same impact on another. Different anime series can evoke strong emotional responses due to their themes, storytelling, and character development.
One anime that is often mentioned for its dark and emotionally heavy themes is "Grave of the Fireflies" (Hotaru no Haka). It's a Studio Ghibli film directed by Isao Takahata, released in 1988. The story revolves around two siblings, Seita and Setsuko, who struggle to survive in Japan during World War II after their home is destroyed by bombings. The film portrays the harsh realities of war, loss, and the hardships faced by innocent civilians.
Another anime known for its emotional impact is "Clannad: After Story." It's a sequel to the anime "Clannad" and is praised for its poignant storytelling and exploration of life, family, and tragedy. The series delves into themes of grief, sacrifice, and the complexities of relationships.
However, keep in mind that these anime series are emotionally challenging and may not be suitable for everyone, especially those who are sensitive to heavy themes. If you decide to watch them, it's essential to be mentally prepared for the emotional toll they may take. Always check the content and ratings before starting any anime to ensure it aligns with your preferences and emotional well-being.