Once Kisling has joined your party, return to Madril and enter the building closest to the exit. The scientists here know of Kisling's renown and will accept donations for research in the name of science. The first donation won't produce anything other than this trophy, but by donating the lowest increment every time, you can eventually obtain a Black Cat Jewel and the Omnibooster (a great accessory). So even though they offer you to donate more, the reward will always be the same (unless you're a charitable soul).
10 sukel
50 sukel
Reward: trophy
100 sukel
500 sukel
Reward: Frozen Bottle (ice damage to enemy target, -5 hp to user)
1,000 sukel
5,000 sukel
Reward: Power Candy (+1 Attack to a party member)
10,000 sukel
50,000 sukel
Reward: Black Cat Jewel (halves health of everyone on the field)
100,000 sukel
500,000 sukel
Reward: Omnibooster (+5 to all stats)