The phrase "again he sees" is correct and usable in written English.
It can be used to indicate that someone is seeing or experiencing something once more after a previous occurrence.
Example: "As he walked through the familiar streets, again he sees the old bookstore that once held so many memories."
Alternatives: "once more he sees" or "he sees again".
When he can see again, he sees that Fawad is holding the Frenchman's metal pencil case.
The fleeing mouse snatches a glance over his shoulder, and when he looks forward again he sees the floor lamp coming closer and closer.
Time and again, he sees his colleagues win or lose business based on the verve of their presentations to clients, not on the validity of their ideas.
Once again, he sees them smiling and then he sees them walking away down a street where yellow lights scatter and regroup sporadically, without any obvious pattern, although Henric knows deep down that everything is determined in some way, everything is causally linked to something else, and human nature leaves very little room for the truly gratuitous.
When Siddhant looks into the future again, he sees the same thing, and is shocked to see Krrish still alive and on his island.
Meeting with the Happy Mask Salesman again, he sees Link has retrieved his ocarina, and hence teaches him the "Song of Healing", which breaks the curse, returns Link to his human form and seals his Deku Scrub form into a mask which has the power to turn him back into a Deku Scrub if needed.
Again and again, he saw life in untold numbers: miniscule creatures, dancing and dashing about.
(Again, he saw plenty of ghosts in singular form — I'm only making a point).
When he looked over his shoulder again, he saw that Gary was losing ground.
As he zipped across the second slide, Anderson reported that again he saw lots of inflammation.
But, again, he saw no reason to deny the firearms application.
