As I was (again) randomly checking online about some Arashi stuff, I cam across a page that compiles proofs/stories that shows how rich the family of these 5 are. And so I've decided to translate them.
Here goes nothing...
AIBA MASAKI
His parent’s house as a chinese restaurant is just for show. In reality, they own a pretty large land in a major area in Makuhari (a place in Chiba). Even their dog house has air conditioning installed. They’re that rich. That’s why he’s okay even if he doesn’t learn how to cook. In Arashi, Sho is portrayed as the young master but in reality, the number one young master among Johnny’s is Aiba, the one always called the “common guy."
SAKURAI SHO
His father is a graduate of Tokyo University and soon to be the Vice Minister of Internal Affairs and Communication while his mother is a graduate Ochanomizu All-girls University and a literature professor at Komazawa University. It seems both his parents are from Gunma prefecture and his mother’s family is quite wealthy and a nobility. In one old episode of Utaban, he brought some stuff found at his grandmother’s house such as a high-end plate and a katana scabbard so it is safe to assume that he is pretty rich.
NINOMIYA KAZUNARI
His great grandfather was a company president.
MATSUMOTO JUN
His family is well-known for being extremely rich. Even without becoming an idol, MatsuJun can survive just by taking after his family’s business (real life Domyouji). His family runs a poultry farm and sells eggs. They also sell these eggs in Rakuten with the tagline 'MatsuJun life' (written as 松潤命). It seems the eggs are really tasty that they were featured once in Hanamaru Market for 500yen a piece. The eggs sell as well as the 'MatsuJun' brand within Tokyo. They are also planning on exporting the eggs to Europe and America.
OHNO SATOSHI
In a music show, they talked about how they spent their Christmas. Ohno answered with 'I spent it with my father and some people from his company. Around 10 people.' Aiba then asked, 'Eh? Is your father someone powerful? President?' 'I don’t really know but it seems that he is,' Ohno answered.