A good compromise so that big tit lovers can be more faithful to the integral character design is to simply draw BOTH sisters together, side by side, so we get the best of both types.

A big part of he character is that she has a complex about her tiny body, which she really ought to embrace because making your enemies underestimate you is an important tactic; you could say that doing that instinctively is Saitama’s OTHER superpower, which was crucial for helping him survive during his transitional period from mortal to Demigod. His relatively low intelligence would have gotten him killed without it before his strength could plateau.