DOZEN'S PROFILE

While Shiro is a shy guy who completely lacks sex ed., or any experience with romantic relationships in general, he is nice, good natured, athletic, actually likes and talented at cooking and housework, accomplished archer and swordsman, the best mage when it comes to swords and would (provenly) need hundreds of years of mistreatment bombing him to be capable of giving up what he has in mind. In other words, he is a dreamguy and every girl on a first-name basis with him(+Ayako, questionably) has at least the hots for him, if not outright love him. The only reason for the former not loving Shiro is that they already loved someone else before they met him(Bazett->Lancer, Caren->Avenger, Rider->Ayako).
Usually in these games either drama ensues as the main character chooses someone, or the girls simply share him, but in this case it goes differently, for two reasons:
1. Shiro is so oblivious to their feelings he doesn't even know most of the time what's going on, and even then he refuses to act like it so he doesn't hurt anyone
2. None of the girls save for Rider has shown willingness to share him with the others

So, what solution did the girls come up with? 'Let's freeload off of his house and enjoy his treatment until someone gets lucky.'

That alone and in itself is bad enough, yet it's not the worst thing. It's the absurd mixup and the weirdness of the household that makes his life a living hell:
- Saber used to disregard her gender, and refuses to act like a woman while she is as girlish as you can get, and also she has a lazy hair that turns her into the evil version of herself if pulled. Has ridiculusly good magical powers
- Rin is a Tsundere buffed up with ridiculusly good, inherited and trained magical powers and loves to mess with everyone else. While overall a good person, she is used to being treated as an idol, and acts like it. What else, oh yes, martial artist
- Sakura has even more ridiculusly good magical powers and been mistreated by her adoptive family so badly (we are talking rape, torture and live vermin put inside her body, people) she ended up mentally broken and while the nicest of the cast otherwise, she loves Shiro like crazy('cuz, she is) and gets violent(and I mean violent) when pissed off
- Ilya is actually Shiro's non blood-related sister who is 20something years old while her body and emotional level stuck as a pirmary school student's, and has two maids(Leysritt and Sella, respectively) who are overhumanly strong trained killers and a crazed impervious giant under her service, and guess what, has ridiculusly good magical powers(actually, this line stands for everyone but Taiga so let's just say it's there from this point forward)
- Rider... where should I start... why she is a nice and shy drunkard, bisexual nerd who turns people into stone by f*king looking at them without her glasses on, addicted to human blood and in her past committed genocide on a regular basis(The 'nice and shy' part in the beginning of this sentence is, suprisingly, not in contradition with the rest, mind you)
- Taiga, Shiro's guardian following his father's death, is a lazy teacher in the local school. Her granddad is a leader of the Japanese mafia. She too is very violent when angry(happens a lot) and a kendo master to boot
- Caren is a priest who emits spikes from her body when evil people are in her relatively close vicnity. Also likes to mess with others
- Bazett is quite normal compared to the rest, aside from being easily distracted by her own thought process, but when LANCER is around... good lord...

And these are just the women he lives with.

So in the end, Shiro willingly keeps these people (and, consequently, his house) together while being way too nice to abuse the fact that these willing and eye-pleasing girls live with him. Bazett, Caren and Rider sometimes help him. Sometimes. When they aren't the cause of the trouble themselves. The only good thing I can say is that it's helluva fun watching this from the outside.