Akiba Guild Hall Raid

The Akiba Guild Hall Raid (アキバギルド会館レイド) is an event that occurs in the thirteenth volume of the Log Horizon series.

Overview
Lelia Mofur and Litka Mofur warn Log Horizon about a Genius, Eirenus, who has prepared to attack Akiba. This premonition comes true when Isaac and several other Black Sword Knights members called back to the city wake up in an area different from where they had fallen asleep. Knowing that this is the work of a Genius, having been warned by Shiroe beforehand, they uncover the level 65 Eirenus and attack him, but are easily defeated and killed due to Eirenus' abuse of the Teacher System.

It is discovered that Eirenus had sucked all the city's Adventurers and Ancients into a Raid zone based on the city, and uses the Teacher System to suppress anyone whose level is above 65 all the way down to level 35. Furthermore, zone connections have been scrambled and thus zones don't connect the way that they normally would (for example, the door to the kitchen of Log Horizon's guild house could now connect to the outside of the Akiba Baths). To even further worsen the situation, it was impossible to contact others with Telepathy, making organizing much more difficult.

Realizing that he and the other formerly-high-level players don't stand a chance against the level 65 enemies, Shiroe has Lelia and Litka (who are at level 65 and thus didn't have their levels lowered) find Minori and have her organize a counterattack against the Genius mastermind, whom he had ascertained to be in the Guild Hall. Minori, upon receiving the message and the intel gathered by Rieze and the Silver Sword members present at the time of the attack, finds members from the Crescent Moon Alliance and Log Horizon to form the Akiba Guild Hall Raid Party in the Crescent Moon guild hall.