Kaworu's dialogue in episode 24 gives clues to the reasons for the Angel attacks: they seek to return to Adam, thus triggering a form of Third Impact which would annihilate humanity and leave whichever Angel that made contact with Adam as the dominant lifeform on the planet:
"Adam: that from which we came. Must one who was born from Adam return to Adam, even though it would destroy Man?...wait...this is not...Lilith?! I see! I understand now! "The Lilim"; Lilith!"Kaworu, however, chooses to sacrifice himself for the future of humanity:
"This is my wish: please, destroy me. Otherwise, you will be destroyed. Only one life-form can be chosen to evade the destruction and seize the future! And you are not the existence which should die. You need the future, it is what you live for!"
Despite his overall importance to the plot Kaworu has less than 13 minutes of screen time (and this at the end of the series, in episode 24). Furthermore, during the last minute of this time, no dialogue or action occurs; it is quite literally a 'static' scene. Kaworu makes a rather more notable appearance in The End of Evangelion, appearing with Rei inside Shinji's mind as the Human Instrumentality Project is being initiated. At first, when the giant Lilith/Rei appears to Shinji, he is terrified by it. It then transforms into Kaworu, a form which Shinji accepts. Kaworu, along with Rei, argues with Shinji in regards to the case of humanity and in favor of individualism and free choice (specifically, in favor of Shinji rejecting Instrumentality). In one of the last scenes, Yui Ikari and Professor Fuyutsuki continue the dialogue started by Rei and Kaworu.
Promotional materials for Rebuild of Evangelion include prominent images of Kaworu in his plugsuit with the other Children. He appears briefly at the conclusion of the first film in conversation with Keel. Kaworu will be the pilot of Evangelion Unit 06 in the second Rebuild of Evangelion film.
The topic is also referred to in largely comedic omake (bonus material).
Patrick Drazen sees Kaworu's offer of love for Shinji to be a tactic that Kaworu as the last Angel used to disarm Shinji, but Drazen also acknowledges that his view is in the minority.
Another important difference in this manga is that Shinji initially does not like or trust Kaworu. Just after their first meeting, Kaworu calmly kills an abandoned kitten that had been following Shinji; his pragmatic reply to Shinji's question of "why" (it was kinder to kill the kitten rather than let it eventually starve to death) made Shinji feel that Kaworu was like Rei when Shinji first met her. Later, Kensuke and Hikari see Shinji and Kaworu arguing. Shinji sees them and runs away, and Kaworu looks up and smiles at them; Kensuke thinks to himself, "Creepy...something inhuman..." After Shinji brings Kaworu to Nerv, he tells Asuka that she needs to open her heart to her Eva in order to operate it; this line was delivered by Rei in the anime. In the aftermath of the battle with Arael, Seele interrogates Kaworu, and he mentions that he finds human emotions and attachments fascinating.
In volumes 9 and 10, Kaworu pilots Unit 02 alongside Rei in the battle with the Angel Armisael. The Angel partially assimilates Unit 02, connecting the already-assimilated Rei to Kaworu and causing him to feel Rei's love for Shinji, which makes him cry. After the battle, Shinji nearly punches Kaworu after he calls Rei a fool. Despite this, Shinji stays in Kaworu's apartment rather than go home to Misato, believing that being around the emotionally distant Kaworu would be more tolerable than being around people who would also be sad about Rei's death. He reluctantly accepts Kaworu's offer to share his bed. That night, Shinji begins to hyperventilate while having a nightmare, and Kaworu kisses Shinji, using the lack of a handy paper bag as an excuse. Shinji becomes angered when he wakes fully and realizes what Kaworu did, and is even more angered when Kaworu asks him if what he felt while connected to Rei was love and attempts more advances. Later, after Rei re-appears, Shinji returns to Misato's apartment with the barest of good-byes, visibly upsetting Kaworu. Volume 11 plays out the same way as episode 24. However, Shinji is confused about his feelings towards Kaworu, and the latter tells the former that Kaworu's death at Shinji's hands will allow him to know truthfully what Shinji's feelings towards him are.
In the following chapter (75), Shinji admits that he was attracted to Kaworu, even though he knew he shouldn't be. With his confused feelings at everyone else he was close with abandoning him, and Kaworu being the only person showing the slightest bit of affection to him at the time, Shinji regrets killing the only person who has ever genuinely cared about him with no strings attached.
At the end of volume nine of the English adaptation of the manga, an article written by the editor Carl Gustav Horn compares Kaworu to the character Satan in Mark Twain's novella, The Mysterious Stranger.
Kaworu was named by screenplay writer Akio Satsukawa. Kaworu's surname "Nagisa" comes from the Japanese word "渚 nagisa", meaning "waterside" or "shore," concerned with sea. It also comes from Japanese movie director Nagisa Oshima (大島渚). Adding to these, the character "渚", when divided, can be read "シ者 shi-sha". The title of episode 24 is "Saigo no shisha 最後のシ者 The last shisha". "シ者" includes two Japanese words "shisha" (the character "シ" only represents the sound "shi"). The first shisha is "使者"; a messenger, or an apostle (an apostle is usually translated for "使徒 shito" into Japanese). The last one is "死者"; the dead.
Gainax renders his name in Romaji as "Kaworu," not "Kaoru" as would be given by most romanization schemes. The reasons for the difference in the naming have not been explicitly detailed by the series' creators; one theory is that the name is based on the original kana of the name Kaoru Genji, from The Tale of Genji.
Kaworu's seiyū Ishida Akira went on to voice Saburou Mutsumi in Sgt. Frog; this is made fun of in the anime by making his (and by extension, Sergeant Major Kururu's) appearance in the anime a parody of Kaworu's breaking and entering into Terminal Dogma in episode 24 of Evangelion, as well as other nods to Evangelion in Sgt. Frog's anime and manga. Ishida would also later voice Athrun Zala in the Mobile Suit Gundam SEED series, another major mecha anime. Interestingly, in Super Robot Wars Alpha 3 (where the characters of Gundam SEED makes their debut), both teens are featured. Also, both teens were close to the protagonists of their respective series (Shinji in Evangelion and Kira Yamato in Gundam SEED), and piloted red mechas.