25. Is there a ban on candidates taking loans in relation to election campaigns?

Source: 
政治資金規正法, 1948 (2022改正)
Political Funds Control Act, 1948 (as amended by Act No.68 of 2022)

第九条 政治団体の会計責任者は、会計帳簿を備え、これに当該政治団体に係る次に掲げる事項を記載しなければならない。
イ　個人が負担する党費又は会費については、その金額及びこれを納入した者の数
ロ　同一の者からの寄附
ハ　同一の者によつて寄附のあつせんをされた寄附
ニ　第二十二条の六第二項に規定する寄附
ホ　機関紙誌の発行その他の事業による収入
ヘ　機関紙誌の発行その他の事業による収入のうち、特定パーティーに係る収入
ト　一の政治資金パーティーの対価に係る収入のうち、同一の者からの政治資金パーティーの対価の支払
チ　一の政治資金パーティーの対価に係る収入のうち、同一の者によつて対価の支払のあつせんをされたもの
リ　借入金
ヌ　その他の収入

Article 9 The accounting officer of a political organization shall maintain accounting books and record therein the following matters pertaining to said political organization.  
(a) Party dues or membership fees borne by individuals: the amount and the number of persons who paid them
(b) Donations from the same person
(c) Donations mediated by the same person
(d) Donations prescribed in Article 22-6, paragraph (2)
(e) Income from the publication of official newspapers and magazines and other undertakings
(e) Income from the publication of party newspapers or magazines or other activities, pertaining to a specific party
(f) Income pertaining to the consideration for a single political funds party, paid by the same person
(g) Income pertaining to the consideration for a single political funds party, where the payment of consideration was arranged by the same person
(h) Borrowings
(i) Other income

Both political parties and candidates should report detailed and itemized revenues, including borrowings.  This implies that candidates can take loans.