Absolutely! The sweetness level of Japanese coffee jelly can be adjusted according to your preference. If you prefer a sweeter dessert, you can add a sweetener of your choice, such as sugar, honey, or a sugar substitute like stevia, erythritol, or monk fruit. Alternatively, if you prefer a less sweet option, you can reduce or omit the sweetener altogether. Keep in mind that some sugar substitutes may react differently with gelatin, so it's best to use a syrup-based sweetener for a smoother texture. Feel free to experiment and find the perfect sweetness level that suits your taste buds.