It seems that 150.70.84.22 belong to Japan and that is not listed as suspicious, harvesters, comment spammers or any combination.
If you have problem with ip address then single block it from accessing your server/site.
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150.70.84.22
Host unreachable
150.26.0.0 - 150.100.255.255
Japan
Japan Network Information Center
Japan Network Information Center
Kokusai-Kougyou-Kanda Bldg 6F, 2-3-4 Uchi-Kanda
Chiyoda-ku, Tokyo 101-0047, Japan
phone: +81-3-5297-2311
fax: +81-3-5297-2312
hostmaster@nic.ad.jp
Japan Network Information Center
Kokusai-Kougyou-Kanda Bldg 6F, 2-3-4 Uchi-Kanda
Chiyoda-ku, Tokyo 101-0047, Japan
phone: +81-3-5297-2311
fax: +81-3-5297-2312
hostmaster@nic.ad.jp
JAPAN150
Updated: 24-Aug-2007 by
hm-changed@apnic.net
Source: whois.apnic.net