Valentine's Day arrives and love is in the air as girls around Japan plan on giving chocolate to their sweethearts. Nagi locks herself in the kitchen and even skips school to make some homemade chocolate for Hayate. Even though Nagi's first attempts end in failure, she keeps soldering on.
Elsewhere, Ayumu Nishizawa buys herself a box of chocolates to express her love for Hayate, but also decides to buy a box of "obligation" chocolates as she can't decide how much she really likes him. So she heads over to Hakuo Academy where Hinagiku is sitting next to a huge pile of chocolate that various sycophants have given to her. She holds a small bag of a chocolate in her own desk to give to someone when Nishizawa asks her to help arrange a meeting with a boy. Hinagiku bristles a bit when she finds out that the boy is Hayate, but she offers her the use of a private office anyway.
Nishizawa walks into the office, then runs out a few seconds later, having given Hayate obligation chocolate. Hayate decides to follow after her, and gives her back the obligation chocolate, and Nishizawa is so moved that she gives him the other box of chocolate as well. Later, Nishizawa runs into Hinagiku and thanks her for arranging the meeting, though Hinagiku appears to be jealous.
Back at the mansion, Maria tries to help Nagi with her own homemade chocolate again, but it turns out all wrong. Hayate meets Maria outside, talks about his meeting with Nishizawa and asks her for the wisdom of her experience on love. Maria keeps up a smile, but reflects in a staggered monologue that she's been so busy with school and then working to the point that she's never had a boyfriend. Instead, she snaps at Hayate and goes into the kitchen to make him some chocolate. However, Hayate finds her working and wonders who she could be making the chocolate for on Valentine's Day.
After getting embarrassed, Maria and Hayate end up in an accidental chocolate-making contest. Hayate ends up making something simple and giving it to Nagi, while Maria eventually gives up and sits by a lake. Hayate decides to give her another piece of his chocolate, in a reversal of the Japanese Valentine's Day tradition.