Can the 'Growth Investment Quota' and 'Tsumitate Investment Quota' of the new NISA be used concurrently?

Absolutely! The New NISA's Growth Investment Quota (成長投資枠) and Tsumitate Investment Quota (つみたて投資枠) can be used simultaneously. This is precisely one of the biggest advantages of the New NISA compared to the old one, making it much more flexible.

You can think of these two quotas as two separate "baskets":

Tsumitate Investment Basket (つみたて投資枠): You can put up to 1.2 million JPY into this basket annually. This basket is primarily for lower-risk investment trusts suitable for long-term, regular investments (like dollar-cost averaging). It's like consistently saving money each month to buy "stable" assets.
Growth Investment Basket (成長投資枠): You can put up to 2.4 million JPY into this basket annually. This basket offers more freedom; besides the funds available in the "Tsumitate Investment Basket," you can also use it to buy individual stocks, ETFs, and a wider range of investment products. It's like having extra money to invest in company stocks you believe in, based on your own judgment.

How to use them simultaneously?

These two baskets are independent, but the total amount you can invest annually cannot exceed 3.6 million JPY. You can combine them freely based on your own situation.

Here are a few examples:

Full Throttle Type: If you have sufficient funds this year, you can fully utilize both quotas simultaneously. Use 1.2 million JPY for regular investments (into the "Tsumitate Investment Basket"), and an additional 2.4 million JPY to buy a few stocks you favor (into the "Growth Investment Basket").
Stability-Focused Type: If you only want to make regular investments, you can use only the "Tsumitate Investment Basket" annually, investing up to 1.2 million JPY.
Aggressive Type: If you are confident in your stock-picking abilities, you could also choose not to use the "Tsumitate Investment Basket" at all and directly allocate the entire 3.6 million JPY to the "Growth Investment Basket" (though you can only use up to 2.4 million JPY in it, as that's its annual limit). The correct approach would be to fully utilize the 2.4 million JPY "Growth Investment Quota" and then use the 1.2 million JPY "Tsumitate Investment Quota."
Flexible Allocation Type: If you only want to invest 1 million JPY this year, you could allocate 500,000 JPY to regular investments and 500,000 JPY to stock purchases, with complete freedom in allocation.

An Important Reminder

While you have the flexibility to combine them annually, remember there's a lifetime total quota limit:

Lifetime Total Quota: An individual can enjoy a maximum tax-exempt quota of 18 million JPY over their lifetime.
Lifetime Growth Investment Quota: Within this 18 million JPY total quota, the amount invested through the "Growth Investment Basket" cannot exceed 12 million JPY over a lifetime.

Simply put, your more flexible "Growth Investment Basket," which allows stock purchases, can hold a maximum of 12 million JPY worth of investments over your lifetime. The remaining 6 million JPY must be filled through the "Tsumitate Investment Basket."

In summary:

Think of these two quotas as two helpful assistants for your financial management: one responsible for steady savings (Tsumitate Investment), and the other for helping you seize opportunities (Growth Investment). You can direct both of them to work for you simultaneously; how you combine them is entirely up to your own strategy and ideas.