It's interesting to read the first pages of chapter 1 after this.
Samurai girl isn't one of his wife party members during the final battle (which are the wives he's travelling with now) but seems to be one of his silhouetted "comrades" in the background who jump out of the wagon to assist against the demon king (long haired sword wielding girl with rectangular armor on her shoulders, hooded mage with a staff + shield of indeterminate gender, masculine shadow with hair that matches up with Kazuya seen at the end of this chapter)