Kendo isn't going to help you firm up like what you want.
Here's what I would do. (and what I have done before)
1. Drink lots of water every day.
(At least 8 glasses or the equivalent thereof. To be a little cras, if your urine is yellow, you're not drinking enough.)
2. Get a min of 8 hours sleep a day.
3. Cut back your portions when eating.
(You'll feel like your not full for a few weeks as your stomach shrinks.)
4. You can also eat like 5-6 meals a day, but very small.
5. Get 20 minutes of non-stop aerobic exercise AT LEAST 3 times a week. (besides Aikido. eg. walking around the neighborhood.)
6. Don't be like every American out there and expect results in one week. Just make lifestyle changes and the pounds will slowly melt away for good.
7. Always consult your doctor before starting any exercise or diet program.
8. Take it easy. If you hammer yourself from the get-go youl burn yourself out, get discouraged, and risk injury.
9. Track your progress. (Sometimes you wont see any change on the scale but if you haven't been doing much lately, don't forget, you're switching fat for muscle.)
10. A light weight-lifting program can help also. The average body burns over 2,000 calories a day just to work. By adding muscle, you burn more calories during the time your body is maintaining itself.