When I was looking into installing one, the contrators I spoke with were going to "sink" it, so no step would have been needed (the tub would have been part of an addition in a single story home, so sinking the tub would not have been too big a deal). I had steps in my last tub and hated them, so that was not an option. As it turned out, I decided against a deep soaking tub after I tried sitting in one - not at all comfortable for me - and got a deep corner tub instead. I definitely suggest trying out a Japanese soaking tub before you decide to get one.

We haven't found we need steps to get into our tub.
It's about 4' long, 30" wide, and 2' deep. We just
sort of sit on the edge and step over into it.

I suggest "trying on" tubs if you can. We went to
a great place (Tubz) that had a lot of them available
to try in their warehouse, and just sat in a bunch
of them until we found one that felt good.

I *love* the deep hot water, and since it's so small,
it's not as wasteful of water as a huge tub.
The only downside is it's really only a one-person tub.

I'd be happy to send you a picture (I don't have a place to host the image).

There are lots of ways to install steps for a Japanese tub. Here's but one solution:

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In most cases, steps really aren't needed. I spend a lot of time in Japan,and I can't think that I know anyone with steps for getting into or out of their tubs. You just swing one leg over the side of the tub, then the other. Even my 78 year old mother-in-law manages it without difficulty on a daily basis.

But if you really think you need steps, follow the link below for some ideas.

Here is a link that might be useful: Diamond Spas Japanese Baths

It just got finished, but this shows how we set up our japanese-inspired, but American style tub (Americh Kyoto).

We've used it once. The steps add interest, and the platform provides a landing surface for bath implements, dinner, candles and the champagne bottle and two glasses.

However, it is much safer and easier to get in and out of the tub by placing your bottom on the edge and swinging, as noted above.

Have you considered a wooden japanese tub?

A solution for an extra deep tub may be as simple as a bench to keep in front of the tub!

Since every tub is custom made, it is possible to add a step to ease ingress/egress. This can also be used as a bench for relaxing before/after the bath.

Most of people tend to think that a wood tub is expensive and difficult to maintain, so resorting to synthetic materials is inevitable.

Actually, if preserved from excessive dryness and maintained with hiba-oil a wood tub can last 30+ years.
I wish you could have the chance to try a real japanese made hinoki tub and make your own opinion...

Here is a link that might be useful: japanese tubs by Bartok design