Hong Kong-based activist investor Oasis Management on Monday revealed it owns over 3% of Japan's Kao, days after claiming the cosmetics and skincare firm could boost its share price by 76% by streamlining and focusing on overseas marketing.

Oasis has been investing in Kao for over four years and engaging with it for nine months, the fund's founder and chief investment officer, Seth Fischer, told a news conference in Tokyo.

The fund has full shareholder rights and is considering options to encourage management to adopt its recommendations, including submitting shareholder proposals, he said.