There are various low-alcohol sakes designed for picky women or light drinking men.
Sake is usually diluted to about 15% ABV, for taste. Those specially chosen not to be diluted (Genshu, 原酒), can go up to 17~18%. Not a huge difference on paper, but you'll strangely feel MUCH more fucked up after even a couple glasses.
Anyways, most low-alochol sakes go from about 6 to 8% ABV.
They either taste much cleaner than normal (almost like water), or are sweeter than normal. Unfortunately, these are pretty much "specialty" brews, and I don't know about the worldwide availability...
A personal favorite of mine is Hofukuzetto by Tsuki no Katsura. I really doubt they can be found outside japan, so here's an abritrary pick from Sawanotsuru (another big producer in Nada).
It's called Tama Usagi, and it's the watery sake I was talking about. It's extremely clean.
Accordingly, however, you won't find a big a punch of flavor as in higher ABV brews. This one has a very light, "pretty" floral aroma. The flavor itself is "water," as previously mentioned, but the finish is kinda toasty. Mmm. Don't go TOO overboard, though, because it's still 12.5% ABV.
The brew is a blended sake (Lol). It's 30% ginjo grade sake + 70% junmai grade. Makes sense, too, as the nose is pretty like a ginjo and tastes ricey-toasty like a junmai.
952 yen for a standard 720mL bottle. I gave this a fucking 6.7/10 in my tasting notes way back, but I didn't like low alochol sakes to begin with.