I actually love their reasons for 'mama' and 'papa'...it's not what people usually think for the 'parenting' positions. It's like, Sho is the mama who can do many jobs, watch out for the little details, and is level-headed even though papa isn't there. Ohno is the unusually laidback papa who watches everyone from behind (as you said 'shield against everything'), but when it's the moment where mama -or any of them- needs him, he will be there. It's a lovely balance that I can't help but be so proud of the Arashi family xD

Hope Sho will talk have stories about his birthday soon!