My wife and I live in a 1LDK around 53m2 now. Currently, our rent is about 6% of our total yearly gross salary. We are expecting a child early next year. (couldn’t be more excited about this!

Or am I looking at this totally in a wrong way? Should I be considering anything else or thinking of it in another way?
for some context:
both of us max out our corporate DC, yearly regular NISA and plan to put in at least 2m+ in NISA next year (aim is 3.6m but it may be out of reach)
we are unsure if we will be in Japan 10 years from now
we don’t have any outstanding debts/loans
we are in our early-mid 30's
both of us non-Japanese citizenship
Edit1: added age
Edit2: added nationality info