Unlike Light Yagami, Minoru Tanaka seemed to have a very different motive, what was his true goal?
Minoru was opposed to using the Death Note himself and his actions in the end boosted Japan's economy as a likely result of everyone under 60 getting 100 billion yen. while these might seem like him being virtuous and possibly altruistic, i believe Minoru's motivation was just to make himself money off the Death Note
this is evident in how he did not care in how the Death Note would be used by a buyer but rather how much they would pay for it, and the money going to the japanese people was just to hide his connection to the auction as Near had correctly deduced that the Auction-Kira would need to collect the money. being under 60 himself, Minoru would still get away with 100 billion yen from the sale but it being impossible to spot his account out of the millions that all received the same amount.