After their last great adventure, the gang heads back to Hinata House to greet Grandma Hinata on her arrival. Granny, however, forgot and is currently traipsing around the Himalayas. Meanwhile, on the Tokyo U campus, Naru finally declares her true feelings for Keitaro and the couple retire to a hotel to consummate their relationship. As one might suspect, there are complications, not the least of which being Nyamo, who has a letter for Keitaro. Naru fears that it is a love letter, but it turns out to be something potentially more devastating - a job offer to become an archeologist for Tokyo U. She's torn about what to do, but finally gives him the note and decides not to stand in his way. Keitaro is overjoyed by the prospect, but can't bear the thought of being without Naru. Just when things seem to be about to work out for our couple, enter Grandma Hinata, who attempts to announce the identity of the girl from Keitaro's past. Try as they might to not hear the truth, Keitaro and Naru are finally confronted by Grandma. At last it is revealed that, yes, Naru is indeed the girl that Keitaro promised to attend Tokyo U. with all those years ago.
Cut to four years later, and a new Tokyo U. wannabe, Ema Maeda, arrives at Hinata House. She is impressed and intimidated by the dorms residents, all now enrolled at the university. Ema quickly learns that our favorite couple is about to be married. When she mistakenly "steals" Naru's veil and literally "bumps" into Keitaro, it threatens to put the kibosh on the wedding plans. But all's well that ends well, with the wedding taking place and sealed with a kiss. And then, just as the newlyweds are about to leave for the honeymoon, clumsy Keitaro steps on Naru's wedding dress, stripping her down to some very revealing lingerie. Some things never change.