In the season finale of "Liar, Liar," Episode 12 brings the intense ASTRAL game to a dramatic conclusion. On the final day of the game, the remaining players—Shinohara Hiroto, Saionji Sarasa, and Shiina Tsumugi (also known as Miss Hundred Faces)—face off in a strategic showdown. Shinohara proposes a new, decisive game within ASTRAL: Crossboard, a board game with 100 squares where the objective is to capture the opponent's base.

The episode unfolds like a high-stakes chess match. Shinohara leverages the turn-based nature of Crossboard to his advantage, forcing both Shiina and Saionji into a position where they must protect him to prevent the other from winning. Just as it seems the game is under control, Kurahashi Mikado, the villain pulling the strings behind the scenes, attempts to cheat by creating corrupted copies of players to seize control of the board.

However, Shinohara's allies, Asamiya Nanase and Enomoto Shinji, thwart Kurahashi's plans. They survive an earlier attack and play a pivotal role in the game's outcome. In a decisive move, Himeji Shirayuki, Shinohara's personal maid, infiltrates Kurahashi's base alongside a team of other maids. They take control of Miss Hundred Faces, eliminating Shiina from the game and bringing about Kurahashi's downfall.

Despite these developments, Saionji manages to save the Ouka Academy's base at the last minute, preventing a complete takeover by the Eimei Academy. In the end, the Eimei Academy emerges victorious in both Crossboard and ASTRAL, while the Ouka Academy secures a respectable second place.

The season finale concludes with Shinohara acknowledging the power of teamwork and friendship. He reflects on how a single lie can change lives and vows to continue his adventures on Academy Island. The episode serves as a fitting end to the season, tying up major plot points while leaving room for future adventures.