I don't think there is a manga of Balance Unlimited, but there is a novel. Of course, you can't read it for free I mean I hope you’ve heard of “copyright”. You have to pay for it because it’s their job. If you don’t want to pay, just simply give it up.
https://www.amazon.co.jp/dp/4101171165/ref=cm_sw_em_r_mt_dp_U_EB8SEbXMFVF07
There's is no manga but here's the novel! https://www.novelupdates.com/series/fugou-keiji/
Anyone know where I can read the Balance Unlimited manga? for free ofc tho lol- thx