The 2000s decade was a period of immense creativity in anime, often overshadowed by the global dominance of the “Big Three” (Naruto, Bleach, and One Piece). However, it was a true Lost Golden Age that produced masterpieces of psychology, mature science fiction, and experimental narrative.
Here are 7 crucial anime from that decade that every fan must watch to understand the era’s depth.
I. 7 Essential Anime That Define the 2000s Decade
These series stood out for their narrative risk, unique visual style, or profound thematic exploration.
1. Monster (2004)
- Genre: Psychological Thriller, Mystery, Seinen.
- Why watch it: Based on the acclaimed manga by Naoki Urasawa, Monster is a slow-burn work of high maturity. It follows Dr. Kenzo Tenma on his quest to stop a young sociopath, Johan Liebert. The series is notable for its realistic approach and its exploration of good, evil, and human nature.

Toradora is missing from this list
I haven’t seen Toradora yet, I guess I’ll have to watch the anime
Oh Code Geass was my favorite mecha anime after Gundam, until I saw Aldnoah Zero and Valvrave Liberator