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At the end of a short introductory narrative full of novelties and action, a necessary transition to the real world follows which resolves some question left long left unresolved.

Synopsis

Without any warning we are catapulted into a flashback that takes us back to the settings and atmospheres, reinforced by the use of sound tracks directly from the past, of Sword Art Online and its floating castle Aincrad.
In it we see glimpses of an event of which we have already seen, in the second season, some flashes: the raid against the guild of player killers Laughing Coffin, in which Asuna and Kirito fought on the front lines as prominent members of the Knights of Blood.

What is shown proposes a scene familiar to us, according to the cliché so loved by the Japanese works of history that repeats itself in a cyclical way, in which Kirito defends Asuna taken by surprise behind her by a potentially lethal assault by Johnny Black and his proverbial poisoned dagger , promptly repelled by the swordsman.
This succession of events brings us back immediately to the present, at the end of what we saw in the first episode, at the end of the almost identical scuffle between the virtual one between Kanamoto Atsushi, aka Johnny Black and Kazuto, although this time the killer "poison" has reached its target.

Although the conflict resolved in favor of the young couple, Kazuto is now life threatening, as the succinylcholine given him caused the boy's cardiac arrest, now hospitalized.

After the arrival of the young man's family, together with a shocked Asuna, we find that the doctors have managed to bring Kazuto to a stable situation, out of danger for his life.

However, due to the prolonged cessation of cardiac functions, the lack of oxygen flow could have caused permanent damage to Kazuto's brain functions, with the concrete possibility of a state of permanent coma.

He is the Lieutenant Colonel of the Japanese Land Self-Defense Forces Kikuoka Seijirou, Member of the Ministry of Internal Affairs in the virtual reality division and employer of Kazuto, whom we met at the beginning of the narrative arc dedicated to the Death Gun case , to reassure the loved ones of the young patient by promising to transfer him with immediate effect to a better equipped specialized structure in order to bring Kazuto back to health.

Although things seem to have resolved for the best, the complications come when Asuna and Suguha decide to visit Kazuto at the hospital where Kikuoka sent him to, where the two girls are denied the opportunity to visit the patient despite being respectively the fiancée and the stepsister.

The unusual circumstance suspects the two girls and, after reporting the event, the rest of the group of friends Kazuto.
With the help of Yui and the cardiac monitoring app, with which Asuna kept the loved one's health under control, the group is able to track Kazuto's movements. Thus they discover that his presence in the specialized hospital was nothing but a frame and that in reality his real location was overseas.

Discouraged by the inability to find the boy, Asuna is immediately motivated by Yui, who reminds her of how Kazuto had never given up during his imprisonment in Alfheim, prompting her to do the same.
With the help of Keiko (Silica), Rika (Lisbeth), Suguha (Leafa), Ryoutarou (Klein) and Shino (Sinon) Asuna and Yui manage to put together the pieces of the puzzle, reconnecting Kikuoka to the Soul Translator project, quest last to the Medicuboid technology from which it was produced and, consequently, to the brilliant mind that spread its design: Rinko Kojiro, introduced at the end of Mother's Rosario as it is closely linked to the Medicuboid.

The woman, colleague and lover of Kayaba Akihiko, creator of VR technology that started the entire franchise, had been indicated as the one who monitored the game session of her beloved during Sword Art Online events.
In a flashback we see her interacting intimately with Kayaba, discussing with him the nature of Aincrad and the reason why he made Sword Art Online what it was.
We also witness a conversation between the woman and Kazuto, where he asks the latter not to eliminate the Seed, used to build all the virtual worlds seen so far, unless you feel nothing but grudge against the late Kayaba.
The woman, who moved abroad, is contacted by Asuna through an email whose contents, initially, we are not told, although it seems to have pushed Rinko to head towards the Rath company structure in the middle of the ocean: Ocean Turtle, a maximum security facility entirely dedicated to the Underworld project.

We find out that the researcher had been requested several times in the structure, but had never accepted the invitation to participate in the project until that day, accompanied by her assistant Mayumi Reynolds. The two women go through all the structure's meticulous and continuous security checks until they reach the research team led by Kikuoka.
It is in this circumstance that Mayumi turns out to be a well-groomed disguise for Asuna, who has come to that structure claiming to discover the situation of Kazuto with the help of Rinko who, given the situation, feels partially responsible for what is happening.

Considerations

Ocean Turtle is an episode that, without a shadow of a doubt, will divide the opinion of the spectators: on the one hand someone will appreciate the attention placed on the events of the real world (much more bland and anchored in the sci-fi reality of the series compared to the VR environments proposed) , especially on the situation in Kazuto; others, however, may find themselves uninterested in this episode and in its narrative nature.

In any case, the return to the real world was a necessary transition and its positioning at the end of Kirito's narrative and his abandonment of Rulid together with Eugeo makes it well positioned within the entire story, finally telling us what happened after the attack by Johnny Black.

The episode is decidedly focused on Asuna, leaving us still in the dark on the reason for Kazuto's presence in Underworld, but it sets up most of the context necessary for that explanation, which will probably be exposed to us in the next episode. As a setting episode it proves to be quite effective, connecting several past points of the franchise and closing several issues.

Compared to the original work, this is the least directly adapted episode, with several omitted considerations on artificial intelligence and how Yui carries out his research. There is no shortage of additions, in particular regarding the involvement of the rest of the supporting cast in Kazuto's research and the use of Augma, directly from Ordinal Scale, which adds an element of real-world interaction with Yui in a plausible and well-constructed way , integrating the content proposed in the film without destructuring the original story.

Another addition is the opening flashback that specifically connects the incident with Johnny Black to the raid on Laughing Coffin, originally shown in the narrative in GGO, an intelligent addition in that it is much more functional in animated rather than written form.

From the narrative point of view the most significant part of the episode lies in the in-depth introduction of Rinko, whose mention in Mother's Rosario seemed to be more of a wink to attentive viewers than a significant presence.

On the contrary, here it proves to be a crucial element of the overall story not only because it provides the means by which Asuna has been able to infiltrate Ocean Turtle (whose name is another quote to Alice in Wonderland) but finally provides a study on the reasons why Kayaba has carried out apparently illogical actions.
Already in the first series he had suggested that Aincrad was based on a childhood dream of his, but his flashback with Rinko makes it clear that this dream had always turned out to be incomplete, as Kayaba had never been able to find out what was on top. This suggests that his participation in the game was an attempt to complete that obsessive dream of his rather than to control game progress from the inside, also giving additional meaning to the choice of making himself the final boss of the hundredth floor of the fortress.

Asuna also deserves special mention in this episode, taking on a more active and spotlight role than previously done and showing that she is as competent, if not more so, than Kazuto.
Even with the more "technical" help of Yui and Rinko, the girl showed remarkable strength and a noteworthy dissimulation ability with her excellent English, the result of her education and high-ranking family background.

As for less narrative aspects, the care in the clothing of the characters is commendable: the avatars have been clearly updated, a sign that the characters have gone ahead in the game and found different equipment and, at the same time, the clothing exhibited in the real world is completely new, unusual aspect of Japanese animation products where the characters usually exhibit a uniform or a constant characteristic outfit for the whole series.

The only technical note of the episode, otherwise excellent from this point of view, is the CGI of the helicopter, excessively artificial compared to the rest of the artistic sector, which in an episode set in the real world inevitably clashes.

As a setup for the events to come and as an adaptation, this episode has done an excellent job, innovating without distorting what has been adapted. The events recounted are not many, but the above will certainly be fundamental for what episode 6, entitled "The Alicization project", promises to tell.