2625. This #kanjipuzzle is about evolution. Start with one character, add a few strokes, and get another, then repeat. 一 -> ? -> ? -> ? -> ? -> ? -> 患

一 -> 二 -> コ -> 口 -> 中 -> 串 -> 患  

一  ICHI, ITSU, hito(tsu) - one

二  NI, futa(tsu), futa - two

コ  Katakana "Ko"

口  KOU, kuchi - mouth

中  CHUU, naka - middle, medium

串  KEN, KAN, kushi - skewer

患  KAN, wazura(u) - be ill, suffer from