Answer:
a) 警 -> 詳 -> 美 -> 奇
警 KEI - admonish, warn
詳 SHOU, kuwa(shii) - detailed, full, familiar with
美 BI, MI, utsuku(shii) - beautiful, beauty
奇 KI - strange, curious
b) 吉 -> 吐 -> 塊 -> 魅
吉 KICHI, KITSU, yoshi - good luck
吐 TOU, ha(ku) - spew, vomit, give vent to
塊 KAI, katamari - lump, clod, clump
魅 MI - charm, enchant, fascinate