When does yugi notice yami?

Answer 1

Well, that's a very broad question that calls for a pretty weird answer.

In the manga series, Yugi is informed of the fact that there is someone else inhabiting his body when he runs into Shadi for the second time. Yugi asks if Shadi has seen his puzzle (which he lent to the museum owner for display), upon which Shadi enters Yugi's mind to find out why he knows about the puzzle. After losing a shadow game to the other Yugi, Shadi returns the puzzle to Yugi and tells him about the presence of his other self, much to Yugi's amusement. However, Yugi himself first takes notice of his memory lapses when he, Sugoroku (Solomon), Anzu (Tea), and Jonouchi (Joey) go to visit Professor Yoshimori (a colleague of the museum owner) at his Archaeology laboratory. He wonders about why he can't remember certain things that happen at all, and notes that sometimes things are a total blank.

He is finally forced to admit his suspicions about his other self's presence right before the events of the fourth stage in Death-T, Kaiba's theme park of death. After Honda is trapped in the room with the falling blocks in Death-T 3, Yugi's emotions begin to overflow. He is caught up in the tension of the moment just before he transforms into his other self, however this time he feels aware of it and tries to prevent it from happening, due to his fear of his unknown other self and the notion that his friends might leave him if they find out. However, Jonouchi and Anzu console Yugi, promising that they will always be friends, no matter what. From this point on, Yugi accepts his other personality's presence and no longer blacks out when his other self is in control.

Finally, the two actually meet for the first time during the Monster World tabletop RPG with Bakura. After being sealed into his game piece figurine, Yugi is forced to leave his body... which, of course, allows the other Yugi to emerge as the player in his place. This is when the two are able to actually meet and see each other for the first time.

In the Toei Animation, Yugi's realization of his other self is much the same as in the source material. The only difference here is that Anzu already knows about the other Yugi, as he has saved her twice already and won her heart with his bravery (even though he doesn't know it himself and is totally oblivious to her affection). There is also less of an emphasis on Yugi's fears of his other self and more so on his fears of what his friends would think.

Finally, in the NAS anime (commonly known as Yu-Gi-Oh! Duel Monsters) this whole sequence is significantly abridged. In this series, the plot devices of Yugi's fears and worries regarding his other self are entirely written out, leaving only the matter of establishing that, "yes, Yugi knows he has another personality now. Moving on!" The whole arc of the gang's battle with the other Bakura in the tabletop RPG is replaced with a duel set in the Duelist Kingdom arc, in which Yugi and his friends' souls are sealed into their favorite Duel Monsters cards. The other Yugi is then the first Yugi present in the game, making for an awkward moment each time one of Yugi's friends was summoned to the field in the form of his or her favorite card. When the original Yugi is summoned in the form of the Dark Magician, he is prompted to answer why there are two of him.

Here is where we have yet another split: in the Japanese version, Yugi implies that he has known about his other self's presence for quite some time and that he has merely been keeping it a secret. However, in the 4Kids English dub (and all other language dubs that extend off of it) Yugi is just as surprised as his friends and says that he sometimes feels as though someone is guiding him in his duels.