Is Teppu Finished? Yes — Complete in 8 Volumes
Yes — Teppu is complete. It ended in Japan with 8 volumes; the final volume came out in October 2015.
Everything below reflects the Japanese edition — the source of truth that runs months or years ahead of English releases — computed from official publication records.
Volumes in Japan: 8 (latest: 鉄風 8, 2015-10)
Next volume in Japan: not yet announced in Japan.
Status: Yes — Teppu is complete. It ended in Japan with 8 volumes; the final volume came out in October 2015.
Serialized since: 2010