The Tunnel to Summer, the Exit of Goodbyes: Ultramarine (Manga) Vol. 4

THE TUNNEL'S SECRET

Kaoru learns that Anzu has been assigned a manga editor. While this a big step towards fulfilling her childhood dream of becoming a manga artist, Anzu isn't happy about it. Kaoru tells Anzu--who is still uncertain whether to enter the tunnel or not--that they should postpone their search. Then he makes a decision:
"Well... shall we?"
What does Kaoru see at the end of the tunnel? All secrets are finally revealed in the conclusion of this bittersweet tale of mysteries and summer love, based on the award-winning light novel!

The final volume!