In most hiragana the horizonal stokes are drawn first, but も is an exception. Is there any reason for this?
I think silvermaple's answer is right, but to add a little bit:
- The katakana
モwas derived from the 楷書体 (block writing)
毛. The initial short stroke was dropped, ending up with two horizontal strokes, and then the vertical stroke.
- The hiragana
もwas derived from the 草書体 (script)
毛, in which, for the sake of writing speed, the vertical stroke was conflated with and became part of the initial short stroke, ending up with the initial long stroke and then the two horizontal strokes.
To quote Toritoribe from JapaneseReference (JRef.com) forums:
も was made from the 草書体[そうしょたい] of the kanji 毛[モウ, け]. So, the stroke order of も was also from the the stroke order of 毛. Incidentally, the stroke order is different in 楷書体[かいしょたい]. (The link of the wiktionary page doesn't work due to garbled characters. Please search 毛 on Wiktionary. The page has the flash of the stroke order.)
And then, on why
モ have different stroke orders, and the origins of
モ was made from 毛 in 楷書体 unlike も. That's why those two kanas have different stroke orders.
ね, わ, れ are from the 草書体 of 祢, 和, 礼 respectively