|Spoiler Alert: This page contains spoilers. Read at your own risk.|
HAR or Home Automation Robots, also known as Humanoid Home Helper or 3H personal chore robot or more simply "Housework robot", is a human shaped housekeeping aid robot. By 2096, it had just hit the market for mass consumption. 
In the framework of the 3H, the communication unit and main sensor are in the head part, a single fuel cell is installed in the chest, taking up both the left and right parts with the electronic brain jammed into it, and information cables and energy cables pass within the skeletal frame.  Based on the assumption that 3Hs are to be used in civilian homes, they are constructed from light weight materials, with its maximum mechanical strength below what could accidentally damage household tools and utensils and also not strong enough to hurt their owners' family.  Its power source is a methanol fuel cell, with an option to refuel methanol so the user doesn't have to worry about exhausting the fuel. To not waste fuel, the model remains on sitting when not in use (as the act of standing is taxing on the power). 
Either the author or the translation team managed to create a contradiction regarding HAR in the Shiba siblings' household.
|“|| As she headed towards the kitchen, a banded loose tail of hair swayed behind her slender back. It was to prevent her hair from interfering with her kitchen work, but, from the fleeting glimpses of the fair nape of her neck, which was normally covered by her long hair, an inexpressible loveliness radiated from the wide center of the neckline of her clothing.
In an advanced country where the use of Home Automation Robots (HAR) was widespread, women — as well as men — who involved themselves with kitchen work belonged to the minority. There were few people who performed any actual cooking in general, such as toasting bread or brewing coffee, with their own hands unless it was a hobby.
And Miyuki belonged to this minority group.
It was not because she was a machine moron.
When friends came to visit, she would normally leave it to the HAR.
But, when together with just Tatsuya alone, she would definitely opt to labor herself.
— In the afternoon in the Shiba siblings' residence at enrollment day, Volume 1, Chapter 1
|“|| Miyuki was currently in the kitchen cleaning up.
She wasn't adamant on doing the dishes herself since she could pass them to the HAR, but their household wasn't equipped with the 3H (Humanoid Home Helper, or simply "Housework robot") that had just hit the market for mass consumption. The two of them unanimously agreed that having a pair of robot arms extending from the ceiling was more of a hassle than anything, so they were better off cleaning up after themselves.
— Miyuki said that if they were too lazy to do even this, their fitness would rapidly decrease.
— In the evening in the Shiba siblings' house after Tatsuya has joined the NSC Technician Team, Volume 3, Chapter 2