While enjoying a fishing tournment Kirito receieves an urgent e-mail from the leader of the guild requesting their return.
Via Crunchyroll
Plot Summary

Asuna shares how her life with Kirito is wonderful
Kirito finds himself bored and unlucky at fishing. Then, a fisherman named Nishida sneaks up behind him. He shows him how to fish, and he catches a large, purple fish. When the man mentions that he can't cook or obtain soy sauce, Kirito tells him that someone can cook the fish. Later, Nishida is amazed at Asuna's cooking, and Asuna comments that Nishida's fishing skill is high. Nishida comments that the lake that Kirito was fishing was designed to be difficult. He mentions that there is a large fish in the lake. Late that night, Asuna embraces Kirito, and Kirito touches Yui's Heart. The two talk about their promises. Next day, everyone watches Nishida cast a lizard into the lake. As he waits, Kirito stands by Nishida who tells me not yet. Then, Nishida switches with Kirito, and Kirito struggles to reel the fish in. With everyone running away from Kirito, the line breaks. Suddenly, a giant, orange fish emerges from the lake. Kirito flees to Asuna's side, and Asuna easily kills the giant, walking fish. Then, Kirito receives a message from Heathcliffe.

Meeting Klein and Egil again
Next day, Nishida shares how he would spend his time fishing in this game, and Asuna shares her experiences with Kirito. She is happy that Kirito is with her. Nishida bids them farewell. At Heathcliffe's meeting, he debriefs them about a boss that wipes out a retcon team and leaving no remains. The boss's room is an anti-crystal trap. Later, Kirito asks Asuna to stay here where she is safe, and Asuna tells him that she will not forgive herself. If Kirito did not come back, she would kill herself. She tells him that whether or not they come back alive, their bodies will be not be able to maintain itself. Over at the portal's site, Kirito and Asuna reunite with Klein and Egil. After the four get acquainted for a bit, Commander Heathcliffe arrives to open the portal. Heathcliffe gives a speech to the army before they fight the boss. Asuna holds Kirito's hand and reassures him that everything's going to be okay. Everyone runs into the boss room to find nothing there.
Suddenly, the boss (Skull Reaper) jumps from above. It kills two soldiers with one swipe of its scythe. Heathcliff blocks the beast, but the boss kills another soldier. Kirito jumps in to protect one soldier. Then, Heathcliff and Asuna join in. Everyone moves in to fight the boss, and Asuna and Kirito combine their attacks to fend off the boss's scythe.
Points of Interest
Miscellaneous
- Japanese Name: "Naraku no Fuchi" (奈落の淵)
- Light Novel Chapter:
- Opening Theme: "crossing field" By LiSA
- Ending Theme: "Yume Sekai (ユメセカイ; Dream World)" by Haruka Tomatsu