High School D×D — Ending Explained

High School D×D's plot is driven by a series of escalating reveals that redefine the world and Issei's place in it. The initial twist of Issei's resurrection as a devil is just the beginning. A major revelation in season two is that the God of the Bible is dead, killed during the last great war. This truth has been hidden to prevent mass panic and loss of faith among angels and humans, and it explains why the celestial factions are in such a fragile stalemate.

Issei's power, the Boosted Gear, is one of the thirteen Longinus, sacred gears capable of killing gods. His rival, Vali Lucifer, possesses the Divine Dividing, the power of the other Heavenly Dragon, Albion. Their destiny is to fight each other for eternity. A key plot point is Issei unlocking the Juggernaut Drive, a forbidden power that taps into the hatred of past Boosted Gear users, granting immense power at the cost of the user's life and sanity. He first uses an incomplete version in Season 3 against Shalba Beelzebub after being tricked into thinking Asia was killed.

The series finale of the anime (Season 4) concludes with Issei's official Rating Game match against Sairaorg Bael. During the fight, Issei achieves a new form called Cardinal Crimson Promotion by using Rias's blood, which allows him to use the power of the Pawn's promotion without being in enemy territory. The season ends on a triumphant note for the characters' relationships, as Issei finally breaks his mental block of calling Rias "President" and confesses his love to her by name, which she reciprocates. The anime story is far from over, as the light novels continue the plot, introducing Issei's own peerage, his ascension to a High-Class Devil, and battles against even more powerful mythological beings, including the reveal of a powerful anti-terrorism group named [DxD] formed by the major factions.

While High School D×D presents itself as a straightforward action-harem series, some alternative readings exist. One interpretation views the series as a satire of shonen power fantasies. Issei's perverted nature and his 'Harem King' dream can be seen as a parody of the typical male protagonist's desire for power and recognition, grounding his epic abilities in comically mundane and lecherous motivations. His power-ups, often triggered by sexual stimuli, could be interpreted as a commentary on the genre's tendency to link male power with female affection.

Another perspective focuses on the political allegory within the celestial conflict. The uneasy truce and complex diplomacy between the angels, devils, and fallen angels can be read as a metaphor for real-world geopolitics. The factions are not monolithic forces of good and evil but complex societies with internal power struggles, extremist factions (like the Khaos Brigade), and a desire for self-preservation. This interpretation suggests the story is less about a battle between heaven and hell and more about the challenges of maintaining peace and balance in a world with multiple competing superpowers.