当然
とうぜん · touzen · JLPT N3 · na-adj
natural
当然 = proper (当) + so (然): it is so, as it properly should be
当 means fitting or proper, as in 適当 (suitable). 然 means so or thus, as in 自然 (nature, naturally). Put together, 当然 means it is so because it ought to be, so it is obvious. The same word, read dāngrán, means of course in Chinese.
当 — small ⺌ + crown 冖 + hand 彐 (simplified from 當: 尚 + 田)
Originally written 當, combining 田 'field' with 尚 as a phonetic. The early sense was 'to match' or 'face' a field of equal value, extended to 'correspond to', 'ought to', and 'serve as'. The simplified form 当 streamlines the upper 尚 component.