While on a train during Tokyo rush hour, high school student Fukaya Mamoru finds himself crushed against his classmate, the silent Fujino Shion (藤乃紫音).

Unable to turn off the vibrator discreetly, Fujino endures the train ride while requesting Mamoru to satisfy her sexual cravings, to which he complies.

Curious about the contents of the potion while also thinking about Mamoru's well-being should it be poisoned or contaminated, Fujino drinks it.

One day after getting caught in a fight between Fujino and Mita, Mamoru falls down on his head, causing memory loss.

[1] On April 26, 2010 the manga was re-released as a two volume kanzenban edition called Strange Kind of Woman (ストレンジ・カインドオブウーマン).

This version only includes the Strange Kind of Woman stories, i.e. it is missing chapters 1 and 5–9 from volume 1 of Hatsuinu.

[2][3] Eros Comix released an English version of the kanzenban edition as A Strange Kind of Woman, with translations by Toren Smith and Studio Proteus.

[4] This OVA is about how Mamoru becomes Shion's boyfriend and how he fears that she values her vibrator more than him even though they have passionate sex.