From a recent news article regarding Japanese gacha law:
"Despite the potentially additive nature of [gacha] games, the Consumer Affairs Agency of Japan ruled that such games were not gambling as long as the player was encouraged by pure moe rather than monetary reward. As long as the girls were deemed cute enough, then a game would still be considered legal. Games where the girls were not cute enough were obviously being played for other reasons, according to the agency, and could be considered unfit for consumers."