I think Neru was all like "It cant be helped, ill lend you some" (and planned to buy one as well, the why of the shacking) and realized she was even more broke than Miku
"Miku wants to buy a Kidsbeer for ¥120. In her change purse she has a ¥100 piece, a ¥10 piece, and a ¥5 piece. Neru approaches her, shaking her head condescendingly. She has a ¥50 piece, 2 ¥10 pieces, and a single ¥. Miku and Neru agree to pool their change and head for the closest pachinko parlor, where they "trade up" (wink) their winnings for ¥2.87 million in addition to their starting amount. What percentage of the winnings will go to Miku, and how many Kidsbeers can she purchase? How much must they each set aside for taxes?"
Miku gets approximately 61.8% of the final pool value, or 1,774,462 yen. Assuming taxes are in the 20% range for winnings (not unreasonable if you've ever seen lottery figures), Miku will be giving up 354892 yen and Neru gives over 219108 yen to The Man. And most importantly, Miku could get 11829 Kidsbeer with her income. That's a Kidsbeer every day for more than thirty-two years.
The real kicker, I think, comes from the effects of investment and compound interest. At even a modest 5% annual interest rate, she still earns 194.45 yen on the first day, thus making a lifetime supply of Kidsbeer (from vending machines, no less) a reality. Note that this value holds for all reasonable tax rates; she would need an absolutely crippling 50.64% tax on her winnings to not exceed 120 yen earned per day at this rate.
