http://jaguchi.com/blog/2017/01/japan-post-redelivery/

JapanPostRedelivery.user.js

// ==UserScript==
// @name           Japan Post Redelivery
// @description    Fix usability issues on the Japan Post redelivery website
// @author         mirka
// @include        https://trackings.post.japanpost.jp/services/srv/search/direct*
// @include        https://trackings.post.japanpost.jp/delivery/deli/*
// @namespace      http://jaguchi.com
// @version        1.1
// ==/UserScript==

(function () {
	var my_postcode = "1234567"; // 郵便番号
	var my_directiontype_code = "1"; // 希望の配達先

	if (window.location.pathname == "/delivery/deli/") {
		redeliveryPage();
	} else {
		trackingPage();
	}

	// Run if this is a tracking page
	function trackingPage() {
		var history_table;
		var btn;

		if (/Absence|ご不在/.test(document.body.textContent) == false) {
			return;
		}

		history_table = document.querySelector("table[summary='履歴情報']");

		// Set up and insert button
		btn = document.createElement("input");
		btn.type = "button";
		btn.onclick = goToRedelivery;
		btn.value = "再配達を依頼";
		with (btn.style) {
			backgroundColor = "#dedede";
			cursor = "pointer";
			fontSize = "14px";
			margin = "10px 0px 30px";
			width = "100%";
		}
		history_table.parentNode.insertBefore(btn, history_table.nextSibling);
	}

	// Go to Redelivery page with tracking number as query
	function goToRedelivery() {
		var track_no = document.getElementsByName("trackingNo")[0].value;

		window.location = "https://trackings.post.japanpost.jp/delivery/deli/" + "?number=" + track_no;
	}

	// Auto-fill Redelivery page
	function redeliveryPage() {
		var directiontype_radio = document.querySelector("input[name='directionType'][value='" + my_directiontype_code + "']");
		var query = window.location.search.match(/number=(\d+)/);
		var my_track_no = query ? query[1] : prompt("伝票番号を入力:");
		var number_type;

		if (my_track_no === null) {
			my_track_no = "";
		}

		my_track_no = my_track_no.replace(/-/g, "");

		switch (my_track_no.length) {
			case 11:
			case 12:
			case 13:
				// 追跡番号
				number_type = "inputTrackNo";
				document.querySelectorAll(".border_box.p_0")[2].style.display = "none";
				document.querySelector(".form_layout.w_327.float_r").style.opacity = .3;
				break;
			case 6:
			case 8:
				// お知らせ番号
				number_type = "inputNoticeNo";
				document.querySelectorAll(".border_box.p_0")[1].style.display = "none";
				document.querySelector(".form_layout.w_328.float_l").style.opacity = .3;
				break;
			case 0: // cancelled or no input
				break;
			default:
				alert("番号の桁数が正しくありません");
				my_track_no = "";
		}

		// Set form values
		document.getElementsByName("postCode")[0].value = my_postcode;
		document.getElementsByName(number_type)[0].value = my_track_no;
		directiontype_radio.checked = true;

		document.querySelector("h2.ttl_line").scrollIntoView();
	}

})();