凯 (kǎi) is a stock 'triumphant' character used for foreign 'Ka/Kai/Cap' sounds;
普 (pǔ) handles 'pu/p';
斯 (sī) is the default character for the English plural -s suffix in transliterations (cf.
詹姆斯 Zhānmǔsī 'James',
戴维斯 Dàiwéisī 'Davis'). Without a dominant real-world bearer, treat as a generic surname/name rendering.