2005. This #kanjipuzzle is about evolution. Start with one character, add a few strokes, and get another, then repeat. 一 -> ? -> ? -> ? -> ? -> 週

一 -> 十 -> 土 -> 吉 -> 周 -> 週  

一  ICHI, ITSU, hito(tsu) - one

十  JUU, tou, to - ten

土  DO, tsuchi - earth, soil

吉  KICHI, KITSU, yoshi - good luck

周  SHUU, mawa(ri) - round, loop, lap

週  SHUU - week