Lesson 321 is the 321st chapter of the Gintama series. It is also the final chapter of the Glasses Arc. In this Lesson, the Yorozuya and Hattori Zenzou confronted the leader of the Shimatsuya to put an end on this group.
After defeating 4 out of 5 assassins who came to Hattori's house, the Yorozuya and Hattori faced the final one - the leader of the Shimatsuya. However, this turned out to be a trap, when everyone was soon bounded and surrounded by other members of this group. As the Shimatsuya were about to attack and kill them, Ayame woke up and stopped them with a wave of kunais shot from her blanket. She thanked the Yorozuya for their kindness (while deliberately forgetting Hattori's name,) and used her repaired glasses.
As soon as Ayame put on these glasses, laser beams were shot out from them and more mechanical weapons appeared from these glasses. Then, she was transformed into a robot, killing all the Shimatsuya members with glasses. After an explosion occured, the dying leader admitted that Ayame was the strongest glasses assassin in Edo.
As everyone congratulated Ayame, Gintoki wondered if he should ask Gengai to make a similar pair of glasses. While so, Ayame thanked everyone for the glasses and used it to destroy Hattori's house with the laser beams, much to his horror.
Characters in order of appearance