For newcomers to the 'Diabolik Lovers' anime, the question of where to start is tricky because the series unfolds like a mood piece built on its central vampire family dynamic, not a plot-driven narrative. If you're trying to get a feel for the atmosphere and the characters' rather intense relationships, I'd suggest beginning with Episode 1, 'Welcome to a World of Nightmares,' followed immediately by Episode130, 'Thirst Awakens / The First Kiss.'
Starting with the premiere is essential—it establishes the premise of Yui Komori arriving at the Sakamaki mansion and introduces the six brothers in their unnerving, predatory glory. You get the baseline: the Gothic setting, the pervasive sense of danger, and the initial confrontations. Jumping to episode 130, which adapts the first routes from the original otome game, gives you a clearer taste of the series' core appeal. Each segment focuses on Yui's interactions with a different brother, showcasing their distinct flavors of obsession and domination. It's a concentrated sampler that lets you see which characters might intrigue you, whether it's Shuu's慵懒 disregard, Reiji's cruel discipline, or Kanato's childish volatility.
Watching these two episodes back-to-back provides a more complete introductory experience than the first episode alone, which can feel a bit disjointed as it races to present everyone. The 'First Kiss' episode leans fully into the psychological horror and dark romance tones that define the franchise. After that, you could either continue sequentially from episode 2 or skip around to episodes focusing on the brother who caught your interest, as the plot is largely episodic. The series truly is about savoring the unsettling vibe and the character dynamics, so starting with a dual-episode tasting menu helps you decide if you're in for the full banquet.